@Anais-And-Stephen0 Airbnb does allow hosts to request that guests sign contracts, however, the listing must disclose the requirement of a contract along with a summary of the terms. This way the subject of a contract and its terms don't get sprung on unsuspecting guests that didn't have any idea it was coming nor had the opportunity to decide to look elsewhere if the terms were too onerous. If this host did not do this, you are not required to sign a contract unless you want to. Here's a relevant link on the subject:
https://www.airbnb.com/help/article/465/can-hosts-ask-guests-to-sign-a-contract
Note that whatever you sign is between you and the host....Airbnb will have no involvement in any disputes.
If the existence of a contract was not disclosed in the listing and you do not want to sign one and the host won't honor your reservation as it was accepted, you can request that the host cancel the reservation so you will get a full refund. Here's how to do this:
https://www.airbnb.com/help/article/1250/what-should-i-do-if-my-host-needs-to-cancel
By doing this, the host will have to accept your reservation as booked or cancel it themselves.
There are lots of property management companies in Lake Tahoe and the Palm Springs area that are requiring contracts without knowing the proper Airbnb procedures.
Hope this helps!