How to register my URL for server to server notification?

In WWDC20, the "Get the most out of Sign in with Apple" 11:50 talks about a new feature from Apple that we can use to get direct notifications about the state of users' sign in.

It says we have to register it in the Developer website, but I can only find the section for registering for the email relay!
Accepted Answer
Go to developer.apple.com, "Certificates, Identifiers & Profiles", Identifiers, select your App, search for Sign In With Apple and click its Edit-button.
The overlay that opens has a section "Server to Server Notification Endpoint" where you can enter your URL.
Thanks, @randomguy. What about the the details of how that endpoint operates? E.g., is it a POST or a GET? Parameters?
How to register my URL for server to server notification?
 
 
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