Please refer to this article Booking Settings on setting up Booking Request mode for Airbnb.
FYI you can also check out this article on Airbnb's cancellation policy for Instant Book Hosts. They are much more lenient on cancelling with no penalty for those hosts who use Instant Book.
If you still want to have Instant Book for Airbnb, and still want to have more control on the people who can book, you can set up
Guest Requirement (on Hostfully PMP > Property's Main Settings tab)
Below you will see a checkbox for "Allow booking request" with an Airbnb logo next to it. If you check this box, guests will have the option to submit booking requests inside of your
booking lead time window. The property must be connected to Airbnb before this box can be checked.
In this example, if you check the box and have your booking lead time set to 48, no one can instant book within the booking lead time on Airbnb, but they can still send you a booking request.
This can offer you as a host more flexibility in accepting bookings. Maybe you are very cautious of allowing instant bookings within 48 hours of the arrival date due to logistics of cleaning the home and ensuring it is guest ready. You can still keep that control of not allowing those instant bookings, while enabling guests to submit booking requests to you in case you do think you can ready home in time.