I don't think I'm not going to be a good teammate in a Fortnite scrim.
Why aren't you going to be a good teammate? You love Fortnite!
I don't care about the team.
It's impolite to join a team and then not be a good teammate. The other people on the team are counting on you, so you should try your best when playing. If you don't try your best, other people aren't going to want to play with you.
I am just going to have fun and maybe join another game.
It's OK to want to have fun so you can play at your optimal skill level. At the end of the day, it's about integrity and being a good teammate. You committed to the team. Suck it up and do your best, then switch teams if you want.