Where is the UMass Center Auditorium?

Without being able to ask any other questions I would assume they are referring to the Campus Center Auditorium which is located in the Campus Center at the bottom of the escalators (near the ATM machines). You can also check the "Campus Center Meeting Room Schedule" in the "Useful Links" section to verify this is where they need to be. If they don't know which building the Campus Center is, saying it looks like a "waffle" usually gets the job done.