We do indeed have 'additional info' planned. When that's implemented, the customer will be able to enter any kind of detail you'd like them to (like their user

We do indeed have 'additional info' planned. When that's implemented, the customer will be able to enter any kind of detail you'd like them to (like their username, MAC address, or something else) and we'd pass that info on to you when they successfully check out. With that, you can then automatically perform actions and deliver the digital product/file.