Joining a ranked team. require wins or games?

Just a quick question that i hope i can get an answer to. I have a silver 4 friend whos joining a 3v3 ranked diamond team. does she need to WIN 10 games to get the diamond rewards or just play 10? (or is it 5 idk.) but ya. do you need wins or just games played? makes me a little salty that she can just JOIN a team for free diamond