Need a "terms and conditions" pop-up that must be agreed to before paypal button

I would like to set up a page where I can have customers fill out a contact form (preferably that feeds into Mailchimp) and review a set of “terms and conditions” before they are able to pay for the service through paypal. Any advice on how to do this? I am not very experienced with coding so a plugin would be great (couldn’t seem to find one) or simple code suggestions.

Thanks!