How to make user active member of a team

I made a test account on a test team to see if a user could join a tournament, and the user is unable to join a tournament.

When trying to click “Join Now”, the message comes up: “To join this tournament you must be an active member of a team that plays this game!”

How do I make a user an active member of a team that plays that game? Is there a simple setting I can change for this?

Thank you for the help!