To allow the ‘Refundable Bookings’ banner in the front-end booking steps, go to Settings > Integrations > Refund Protect

Once in this page:

Enable Refundable Booking >>> Yes

Optional Vs Mandatory

The second option in the above screenshot gives you the possibility to make the Refundable Booking as a mandatory option (If Yes is selected). On the other hand, if you select No, the guest has the option to either opt-in or opt-out for the booking protection.

Banner if mandatory

Banner if optional