is it a ATW or an AED

I would take the existing mass airflow sensor off and visually compare it to the two they are asking for. Or, a dealership should be able to tell you over the phone if you give them your VIN.

Check your engine block under the audi cover. Your engine type should be stamped on the metal. If you can't find it, i'll send you a pic on where to look. But it should be right on top when you take off the cover.