Sign in with Apple allows you to use Hide My Email to keep your personal email private when you use Sign in with Apple to create a new account with an app or website.
When you select this option in Sign in with Apple, the Hide My Email addresses created use the address domain @privaterelay.appleid.com.
If you find your email address is not working when logging in, then try your Apple Privacy email.
Here are the steps to locate this email.
On your iPhone or iPad:
1. Open the Settings app, then tap your name.
2. Tap Sign in with Apple. From here, you can see the apps and websites that are using Sign in with Apple. To see if you used Hide My Email for a particular app or website, choose the app or website from the list. If you used Hide My Email, you should see the @privaterelay.appleid.com for that app or website.
On your Mac:
1. Choose Apple menu > System Settings.
2. Click your name, then click Sign in With Apple.
3. Choose the app or website.