I had the same issue the invite would show up on the top right corner of the screen for half a second and goes away.
You have to both add each other on the EA App and one of you would host an online game with EA server and invite the other from there.
I played on PC and my friend who purchased the game was on PS5. What I did was just ready my cursor where the accept button would pop up and spammed it on time when my friend sends the invite. I managed it somehow and was successfully in the game with her. It’s as if the game puts you two into a mini game before it even starts.