help! privaterelay.appleid.com

I logged on to a ticket site yesterday with my Apple ID , and bought some tickets which were sent to my by email.

I didn't receive them, and went back to see where they were sent. This was not to the email address I had given them, but rather to this privaterelay.appleid.com. The email seems now to be lost in the ether, and I have no idea how to access it.

All thoughts / tips from the hive mind would be welcome. Thanks in advance