Thank you for your inquiry.
It depends which train you take. If the train stops in Baar, you can buy a ticket Zurich Airport - Baar. From Baar the Tell Pass is valid. But if the train stops in Zug (without stop in Baar) you have to buy a ticket Zurich Airport - Zug. The area of validity of the Tell-Pass can be found here.
Have a nice day. Greetings ZoeS