k=dlmread('11032020_2020-11-25_17-40-55_m1.ascii', ' ',[585 3 1457 4])
asks it to skip 3 columns and that the reading should proceed to the column that would be skipping 4 columns. Writing that a less confusing way: it asks to read column 4 to 5.
The delimiter has been set to space, and
When a delimiter is inferred from the formatting of the file,
consecutive whitespaces are treated as a single delimiter. By
contrast, if a delimiter is specified by the DELIMITER input, any
repeated delimiter character is treated as a separate delimiter.
so when we examine
11/3/2020 5:06:03.078 PM, 0.0058, 0.0663
1234 567 89A BC DE
15 delimiters and columns 4 is empty and column 5 is '11/3/2020' which is not numeric.
The error message implies that it treated the hour 5 as column 4, and that then it is positioned to the beginning of ':06:03.154 PM,-0.0432,0.0235' looking to read a numeric value. But that location begins with ":'
If you had used comma as the delimiter than 0.0058 and 0.0663 would be columns 2 and 3, which would be suitable for [585 1 1457 2] range.
