Options if our flight to zurich was cancelled for rescheduling trip

You have to contact the RS tour office.

Did the airline offer you an alternative?

Do you have travel insurance?

What is your cancellation policy?

For tours departing Jan. 1 -Dec. 31, 2025, tour deposits are fully refundable for 30 days from the date they are received, unless otherwise noted in our 2025 Tour Conditions. For tours departing Jan. 1–Dec. 31, 2024, tour deposits are 100% refundable for up to 120 days before the tour departure date or unless otherwise noted in our 2024 Tour Conditions. Once your deposit refund date has passed, your deposit will not be refunded, but may be eligible for a tour credit as long as your cancellation is received prior to your final payment due date.

This forum is NOT the RS Tour office.
RS contact info-- https://www.ricksteves.com/about-us/contact-us
They will explain what they can do for your situation

Can you not get another flight perhaps with a different airline?

“ to call the Rick Steves office as soon as it opens in the morning”

Most tour operators have a number that one can contact in case of emergencies. Does Rick Steves not have that???
It’s too late now and I appreciate the OP didn’t think of it on Friday, but the best thing would have been to contact RS on Friday immediately when your flight was cancelled. Perhaps you could have taken a flight the next day and local transport could be arranged so you could catch up with the group.

We just signed up for the Rick Steves Switzerland Tour during the first two weeks in August,

This from another of OP's posts.

Seems there should be time to schedule another flight as the earliest August RS Switzerland tour starts Aug 4