I only edited the template to see if the button itself would show up. It seems it's not recognizing $tournament->canJoin, so the button won't show up.
I currently have two teams created, one is owned by me and the other is owned by another account. When I've created a tournament, I've tried both adding my team first and the other team as well. While that team may be in the tournament, no one else can join with their team.