Within the Orders tab...
Once you enter the "Orders" tab in the Single dashboard, locate the order you're looking to manually fulfill.
You can do this by entering the order number or fan email into the search.
If a digital download is associated with the order, you will see a link button next to the paper airplane. You can copy that link and pass it along to the fan or you can select the paper airplane icon and resend the link to their email address.