The preferred method to provide digital purchases to customers is via galleries renditions produced by Publisher. For this approach the following conditions must be met:
Digital purchases are can be made using either the Paypal or invoiced checkouts. To enable digital purchases for invoiced checkouts, set Enable invoiced checkouts for digital downloads to 'yes' in the Checking Out section of the Cart Settings.
Digital purchases made via the invoiced checkout are not immediately available for download, unless the item total is $0. To enable downloads for an invoiced order, login as admin, find the order in the Orders section, and mark the order as paid. The customer will then receive a notification email that downloads are available.
Note, that if you intend to use the cart for free downloads, it is recommended to change the minimum order amount for carts to $0.
Digital purchases can also be uploaded manually, for renditions that are not produced by Publisher. The following conditions must be met for manually uploaded digital purchases:
Backlight Cart lets you sell digital downloads before having the files available on the server. To enable this feature set Enable Offline Digital Purchases to 'yes' in the Checking Out section of the Cart Settings. Purchases can be fulfilled via the View Orders page. Items requiring uploads are noted in the Digital Purchases column. Click Manage, followed by Edit to upload files.