Right now if you just unzip the one file to the right place everything 'just works' regarding all the textures.
Only time you have to mess with it is if you wanna use all the alts, which is drag and drop in explorer.
For the rosters/dynasty you need a memory card file which lots of people have posted here through the years.
If you did want to swap uniforms to an alt, its shown here briefly:
https://www.youtube.com/watch?v=xz2XGA7GtaM
Look at the timestamps in the description.
Just a couple folder copies and then pressing F9 twice.