Hi

To add users to a role after purchasing a product you have to look into Membership Product Types.
Basically you create a Membership Product Type and add select this newly created Product Type on the Product you want to have the role added.
See the howto here: https://hotcakescommerce....ership-Product-Types

I like MooreCreative's idea for this as well. You can definitely show the download multiple times. It would require an interesting update to the custom viewset. However, the user experience and ongoing maintenance would not be great.