Help adding checkbox below payment options

Good evening community, sorry to bother you. I was wondering: does anyone know how to add a checkbox with a small descriptive text between the payment methods and the button to confirm the purchase? The idea would be that if the checkbox is marked, it also appears attached to the order in the body of the email. The website is in development, but I’m attaching a link with an image for you to see what I need:

https://drive.google.com/file/d/1CihV65yVsAopVfU0GfbHoQTw-ZZL3KsA/view?usp=sharing

Thank you very much in advance!