Scratch that too. As it turns out, it's just a visual bug in the menu... You need to keep L1 and R1 mapped the wrong way there, then it's correct when playing.Apart from that, they changed the button to switch players to R1. I mapped it back to L1, and guess what, it doesn't have any effect. What on earth is this?
So I was finally able to play my first match, and it's pretty similar to FIFA 20 in general. The AI was very effective on Legendary, I ended up losing 2-5...