Sign in with the Google account you use for MTM — no password, no link to keep track of.
Still have a personal link from Ben? That keeps working too.
Nothing is wrong with your account — the studios just are not open to you yet.
You can see the schedule but not book a studio yet. If you are on the MTM 3120 practicum, this is the view you want — find a session you would like to assist on and contact the student running it.
Other students can see this so they can ask to assist on your session.