Friend can't make character on my world?

I'm really not sure where to put this questions. I tried searching but didn't see anything about this issue.

I have a friend who recently bought the game but when he started his character he chose Primal Excalibur (Legacy). I'm on Coeurl which is on Aether (I think). He's trying to make a new character to join me but he can't figure how to switch to Aether for his second character. How can he do this? We're both on the PC. Thanks.

I figured it out finally. After trying for days I found the answer. Data center! This game really isn't just easy to do, is it? Sheesh. Nothing should be this complicated. It's like it's complicated simply for the sake of being complicated.