Hi, @Iain129 . I use Airbnb as a guest (and a host), and Paypal used to show as a payment method option. Then when I had to redo my Payments and Payouts, it disappeared and only the options you mention showed up for paying. The good news is that last month when I booked a stay, Paypal was in the dropdown as an option when it came time to pay. It doesn't sit in Payments and Payouts anymore, but it was usable at the time of booking. I suspect, because I think I read it somewhere, that it has to do with the security deposit. A credit card is necessary for the security deposit hold, but Paypal is fine for paying for the booking.
If you are cool with everything else, then enter a credit card for the record, but just pay with Paypal when you book.