If someone invited you to join a team account, you should have received an email that looks something like this - look for the one-time use team invitation code.
Important: your invitation code can only be used once, so if you log out or get a new device after joining your team, you can log back in using the email address and password you entered when you first joined.
On the dashboard, tap "Accept Invite"
Enter the one-time use invitation code, then tap the "Continue" button
Follow the on-screen instructions to log in or create a new personal Playmaker account