In reply to Tomreynolds396:
The first thing to note is that there's no such thing as a free hut - for the unmanned ones and winter rooms in other huts you are expected to pay. Normally it's between 20 and 30 CHF and this helps pay for the maintenance and wood/gas supply. Even then most such huts have to be subsidised by members of the Swiss alpine club.
There will be either an honesty box, or more likely, payment slips that you can take to the post office once you arrive back in civilisation.
This year thanks to Covid, you have to reserve your place in unmanned huts either via a website or by telephone. This is to ensure that the place isn't overcrowded and that contact tracing can take place if needed. The link above to the SAC site gives you links to the individual huts which explain the procedure.