You can have your registrants agree to Terms & Conditions (or sign a waiver) before checking out.
Start by adding a Terms field to your page.
You can display your terms as Text or a PDF.
For text, type the specifics into the Agreement Text box.
For PDF, you'll be given the option to upload a file.
By default, the field will require the users to check a box. But if you prefer to collect a signature instead, toggle this option on:
Hit done to save your changes.