Terms and conditions pop-up

I have a website running on Woocommerce. I sell my books both as e-book and printed book. I use the variations options in the products page so that buyers can choose which one they want. When they choose e-book, a short description text is shown as a default feature of Woocommerce. I need this description to be shown in a pop-up window with two buttons: "Agree" and "Disagree". If they choose Disagree, "Add to Cart" button will not be shown and there will be no sale. If they choose to agree, they can buy the product as usual.