For publishers who want a hosted solution without managing plugins or servers, the Shopify integration is the gold standard.

EditionGuard offers "turnkey" plugins that handle the heavy lifting of fulfillment by providing instant download links to customers at the time of transaction. Magento DRM: eBook DRM Solutions - EditionGuard

You could upload files to EditionGuard manually and copy/paste download links into emails. But you shouldn't. Here is why integrations win:

EditionGuard is a fantastic DRM service, but it is not a shopping cart. To sell books effectively, you need to bridge the gap between your and your security .