Users dont get the file they paid for
Using Jamroom
The most likely scenario is paypal is not sending a message to your server to tell jamroom that the file has been sold. If that was happening, there would be an entry in the activity log.
It would be either:
jrPayPal: processing incoming transaction:
jrPayPal: invalid notification received in webhook
If neither of those are in your activity log, paypal did not tell jamroom that an item was sold.
If thats the case, check if you have an IPN set at paypal pointing to the wrong url.