I wan to add download to to my every product on the website(wordpress website) When the user clicks on the download button. I want to present him with amember signup form if not a member or sign in form if he is already a member and not logged in. After he login, i want payment transaction to happen. After the customer payment is verified, I want him to be able to download that product( that same product ). How do I do all this? Every and any help would be greatly appreciated. Any link, just anything. Thanks!!