How do I share payment information with an other server?

My brother built a website on Wix and added a shop to it. The items for sale are granting access to a music player which I am hosting on my root server. So I need to validate that a user is eligible to use that item on the music player.
So, I either need to get something like a transaction data package transferred to my server whenever an item is successfully sold or I make an api call to wix to get items that belong to a user sending the users email as an id.

How do I do that?