Plugin doesn't see the RSVP as paid

I have an event requiring payment. I paid to attend the event at PayPal and the event came back with this URL:

But the plugin doesn't show the user is paid, and neither does the front-end code. I'm less concerned about the front-end code at the moment because of how much customizing I've done, but why didn't the plugin register the RSVP as paid?

Thank you