Thank you for your question.
It depends on many zones of ZVV you already have included in your travelcard and also which connection are you taking.
If you have a ZVV only travelcard, but you want to travel in a Z-Pass region (this means ZVV+Ostwind / ZVV+Schwyz Zug / ZVV+A-Welle), you need a Z-Pass ticket. It means the ticket has to start in the ZVV region and end in the Schwyz/Zug region.
In your case, you buy a ticket from the last train stop in your last ZVV zone to your final destination in the Schwyz/Zug zone.
Specifically, if your ZVV travelcard is valid up to zone 152, you buy a ticket from Wädenswil to Einsiedeln, for a total of 5 zones (152, 153, 181, 679, 680).
For any other question please call pur colleagues at the SBB Contact Center (0848 44 66 88, CHF0.08/min): they will be able to give you a personalized answer, based on you travelcard and your chosen connection.
I wish you a good day and a happy New Year.