You can add terms & conditions and make it mandatory for the customer to accept your terms to complete the online check-in.
How It Appears To The Customer
How To Enable It
Add your Terms by going to Settings > Guest Journey Editor > Rental Agreement
Go to Settings > Guest Journey Editor > Journey Editor & Toggle the switch 'ON' for 'Collect Acceptance of Terms & Conditions'
You can make this available for all booking sources or specific sources as you wish.