Generally, you can make a button and set it up to direct buyer to a landing page that tells the buyer that the payment is completed and could simply contain the download url, however that is not a secure way of dispersing downloads. The url can get out there without people paying for it. PayPal offers Digital Goods Payments Processing that could distribute digital goods securely upon payment. For more info: https://www.paypal.com/webapps/mpp/digital-products
... View more
