Paypal Integration

Hi,
I’m trying to Integrate PayPal into my xojo web app to function like an “online store” for let say downloadable content, but have trouble understanding how paypal would communicate with xojo confirming that the payment was successful and “unlocking” the content.
Is this possible?

*apologies if my English is bad xD … Grammarly tried its best.

https://forum.xojo.com/38491-creating-a-paypal-listener/0