Rental agreement

is it possible host can upload a rental agreement and the user can accept that agreement while booking a house, every host can upload their own rental agreement for their property ?

In the current version, the easiest way would be to add a custom Textarea or Attachment attribute for listings and display it somewhere on the listing page (using the Display Areas). Then you can set the common booking terms page in HivePress/Settings/Booking that users have to accept, and add a clause to these terms that they also include the host-specific terms available on the listing page.