Hi @Ben4894
Welcome to the Community Center.
Asking for payments off-platform is generally not allowed, but I did find this article, which states that Resort Fees can be charged.
It also states that these fees must be detailed in the listing description and included in the price breakdown prior to booking, and they are usually charged before the stay, at check-in, or within 48 hours of checkout.
This means that guests should always read the listing description and price breakdown very carefully, so that they are aware if these fees could apply before committing to booking a listing, and giving them a chance to find another listing without the fees if needed.
Should a Host try and charge for a fee that is included on the fees that Hosts can charge directly, but which hasn't been detailed and agreed as above, then I'd recommend that the guest contacts Airbnb Support for assistance.
Jenny