% load stuff from the mat files:
d1 = load('matlab_d1.mat','d1').d1;
ff = load('matlab_ff.mat','ff').ff;
d1
d1 = 1x42 table
      Name      Dwmy    LS_abilitaLong    LS_abilitaShort    LS_long    LS_short    LS_th    LS_minTrades    LS_avgEquity    Avg_abilitaFilter    Avg_mode    Avg_period    Avg_th    Avg_minTrades    Dev_enable    Dev_enableTestDN    Dev_enableTestUP    Dev_devNumDn    Dev_devNumUp    Dev_periods    Peak_enable    Peak_period    Peak_minTrades    Rank_enable    Rank_period    Rank_mode    Rank_type    Rank_minTrades    Rank_maxCat    Rank_using_type    Rank_using_timeframe    Rank_normalize_by_cashvola    Backtest    Cormode    CorTH    BackAdvanc_tradeLMT    BackAdvanc_shiftC    BackAdvanc_cloops    Degrade_enable    Degrade_initialDeg    Degrade_degressMode    MaxPercPortfolio_Disable
    ________    ____    ______________    _______________    _______    ________    _____    ____________    ____________    _________________    ________    __________    ______    _____________    __________    ________________    ________________    ____________    ____________    ___________    ___________    ___________    ______________    ___________    ___________    _________    _________    ______________    ___________    _______________    ____________________    __________________________    ________    _______    _____    ___________________    _________________    _________________    ______________    __________________    ___________________    ________________________
    "TEST_1"     31         false              false            9          2          0           16              0                  0               1            4           40           16              0                1                   0                 1               1              150             0              0               12               0              6             1            1              16               3                1                    1                          0                    1           1       0.75            0.375                 0.75                   2                  0                  100                     0                        0            
ff
ff = 1x42 table
    Name    Dwmy    LS_abilitaLong    LS_abilitaShort    LS_long    LS_short    LS_th    LS_minTrades    LS_avgEquity    Avg_abilitaFilter    Avg_mode    Avg_period    Avg_th    Avg_minTrades    Dev_enable    Dev_enableTestDN    Dev_enableTestUP    Dev_devNumDn    Dev_devNumUp    Dev_periods    Peak_enable    Peak_period    Peak_minTrades    Rank_enable    Rank_period    Rank_mode    Rank_type    Rank_minTrades    Rank_maxCat    Rank_using_type    Rank_using_timeframe    Rank_normalize_by_cashvola    Backtest    Cormode    CorTH    BackAdvanc_tradeLMT    BackAdvanc_shiftC    BackAdvanc_cloops    Degrade_enable    Degrade_initialDeg    Degrade_degressMode    MaxPercPortfolio_Disable
    ____    ____    ______________    _______________    _______    ________    _____    ____________    ____________    _________________    ________    __________    ______    _____________    __________    ________________    ________________    ____________    ____________    ___________    ___________    ___________    ______________    ___________    ___________    _________    _________    ______________    ___________    _______________    ____________________    __________________________    ________    _______    _____    ___________________    _________________    _________________    ______________    __________________    ___________________    ________________________
    TEST     31         false              false            9          2          0           16              0                  0               1            4           40           16              0                1                   0                 1               1              150             0              0               12               0              6             1            1              16               3                1                    1                          0                    1           1       0.75            0.375                 0.75                   2                  0                  100                     0                        0            
Name in table d1 is a string array:
class(d1.Name)
ans = 'string'
But Name in table ff is a character array:
class(ff.Name)
ans = 'char'
To combine them they've got to be the same type, so you've got to convert one or both to something else. Easiest is probably making ff.Name into a string:
ff.Name = string(ff.Name)
ff = 1x42 table
     Name     Dwmy    LS_abilitaLong    LS_abilitaShort    LS_long    LS_short    LS_th    LS_minTrades    LS_avgEquity    Avg_abilitaFilter    Avg_mode    Avg_period    Avg_th    Avg_minTrades    Dev_enable    Dev_enableTestDN    Dev_enableTestUP    Dev_devNumDn    Dev_devNumUp    Dev_periods    Peak_enable    Peak_period    Peak_minTrades    Rank_enable    Rank_period    Rank_mode    Rank_type    Rank_minTrades    Rank_maxCat    Rank_using_type    Rank_using_timeframe    Rank_normalize_by_cashvola    Backtest    Cormode    CorTH    BackAdvanc_tradeLMT    BackAdvanc_shiftC    BackAdvanc_cloops    Degrade_enable    Degrade_initialDeg    Degrade_degressMode    MaxPercPortfolio_Disable
    ______    ____    ______________    _______________    _______    ________    _____    ____________    ____________    _________________    ________    __________    ______    _____________    __________    ________________    ________________    ____________    ____________    ___________    ___________    ___________    ______________    ___________    ___________    _________    _________    ______________    ___________    _______________    ____________________    __________________________    ________    _______    _____    ___________________    _________________    _________________    ______________    __________________    ___________________    ________________________
    "TEST"     31         false              false            9          2          0           16              0                  0               1            4           40           16              0                1                   0                 1               1              150             0              0               12               0              6             1            1              16               3                1                    1                          0                    1           1       0.75            0.375                 0.75                   2                  0                  100                     0                        0            
Then the operation works:
ff(end+1,:) = d1
ff = 2x42 table
      Name      Dwmy    LS_abilitaLong    LS_abilitaShort    LS_long    LS_short    LS_th    LS_minTrades    LS_avgEquity    Avg_abilitaFilter    Avg_mode    Avg_period    Avg_th    Avg_minTrades    Dev_enable    Dev_enableTestDN    Dev_enableTestUP    Dev_devNumDn    Dev_devNumUp    Dev_periods    Peak_enable    Peak_period    Peak_minTrades    Rank_enable    Rank_period    Rank_mode    Rank_type    Rank_minTrades    Rank_maxCat    Rank_using_type    Rank_using_timeframe    Rank_normalize_by_cashvola    Backtest    Cormode    CorTH    BackAdvanc_tradeLMT    BackAdvanc_shiftC    BackAdvanc_cloops    Degrade_enable    Degrade_initialDeg    Degrade_degressMode    MaxPercPortfolio_Disable
    ________    ____    ______________    _______________    _______    ________    _____    ____________    ____________    _________________    ________    __________    ______    _____________    __________    ________________    ________________    ____________    ____________    ___________    ___________    ___________    ______________    ___________    ___________    _________    _________    ______________    ___________    _______________    ____________________    __________________________    ________    _______    _____    ___________________    _________________    _________________    ______________    __________________    ___________________    ________________________
    "TEST"       31         false              false            9          2          0           16              0                  0               1            4           40           16              0                1                   0                 1               1              150             0              0               12               0              6             1            1              16               3                1                    1                          0                    1           1       0.75            0.375                 0.75                   2                  0                  100                     0                        0            
    "TEST_1"     31         false              false            9          2          0           16              0                  0               1            4           40           16              0                1                   0                 1               1              150             0              0               12               0              6             1            1              16               3                1                    1                          0                    1           1       0.75            0.375                 0.75                   2                  0                  100                     0                        0            
