How do I sell digital products on Shopify?
Updated
Install a downloads app first
Install a digital downloads app before you create the product, attach the file to the variant rather than the product, untick "this is a physical product" so no shipping address is asked for, then place a real test order and check the link works on a phone.
Those four steps are where nearly every broken Shopify download comes from.
Turn off shipping on the product
Untick "this is a physical product". If you forget, buyers are asked for a shipping address and some will abandon the checkout.
Also set inventory to unlimited so the product never goes out of stock.
Test a real purchase
Place an order yourself, with a real card if you can, and check the email arrives and the link works.
Then check it on a phone. That is where most buyers will open it.
Write the thank-you page properly
Put the download link on the order confirmation page as well as in the email. Emails go to spam; the page does not.
This one change removes most of your future support messages.