Raspberry Pi support package setup

When I attempt the hardware setup for my raspberry pi 3B I run into issues with sudo permissions. I am attempting to "customize the existing operating system running on my hardware" rather than "Setup hardware with mathworks raspbian image" but the operating system that is running has a preset sudo username and password from the developer that I don't have access to. Since I can use sudo commands in the terminal, I am looking for a way to customize the current operating system from the terminal of my pi using sudo commands rather than using the hardware setup provided by Mathworks. Any and all help is much appreciated!

-Matt