If you have specific requirements for booking, and you want to make sure that customers booking with you follow these requirements, then you can use the Yes/No Custom Field. This add-on type has a a setup option that will require your customers to select 'yes' in order to complete the booking.
To setup, navigate to Setup - Custom Fields. To create a new custom field, select Add new custom field at the bottom of the page.
Choose the Yes/No custom field, then select Next.
in the Setup page, include a short name that should include an "I understand" or "I agree" statement. Add a longer description as needed.
*Note - keep the Name short and concise as you only have a maximum of 40 characters.
Save your changes. Next, to assign this custom field, go to Products & Reservation Rules under the Setup tab. Select the rental that you want to show this statement, then navigate to the Customer Information page.
Set this custom field to "Required". This selection will actually require the answer to be Yes in order for the customer to complete the booking.
At checkout, if a customer doesn't select Yes for this custom field, they will receive an error message: