I don't believe that PayPal will provide any service like that.
What you can do is set up the "re-direct" page with them that sends the user to a specific page on your site after a successful sale. There you could provide a link to the download.
If you use WordPress I believe there are some free eCommerce plugins that work with electronic subscriptions. They would tie into PayPal and provide a secure way of offering the link to paying customers only.