Swiss travel Pass -- where to buy

You can buy it at most large train stations when you arrive in Switzerland.

You can also buy from the SBB website or app if you wish to purchase ahead of time. You will need to enter the day you wish the pass to start. You will have the option printing the pass out and you will also have an electronic copy you can keep in your smart phone.

https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests/swiss-travel-pass.html

Unless you are traveling to Switzerland in the immediate future, I suggest waiting to purchase until you are actually in Switzerland as the pass is not refundable.