How can I regain access to my Apple ID Relay inbox?

Hi, Apple Support Team I would like to report some issue.

I have signed up with an app using Apple ID relay, and for some reason I got logged out. Now I don’t have the password and in order to get the password they send a link to the Apple ID relay - which I don’t have access to because I have no idea even where it is or how to view emails sent to it, may I know how to access your Apple ID relay inbox.

if you receive this email please help me as soon as possible.

[Re-Titled by Moderator]