I can't create my profile name to even play the game

I bought the game and I even have the Xbox Game pass but for some reason I can't make a username on my PC. I haven't downloaded it at all on my Xbox so I doubt that's the issue. I was told that it's a "duplicate" but I'm not even sure what that is. I really hope I could get some help because I love this game and would love to play it again after so many years