If you signed up using Sign in with Apple and chose Hide My Email, Apple generated a private relay email address for you. This email will look something like wasd1234@privaterelay.appleid.com.
On iPhone or iPad:
Open Settings.
Tap your name (Apple ID, iCloud, Media & Purchases).
Select Password & Security.
Tap Sign in with Apple or Apps Using Apple ID.
Choose the Vector app.
Your Relay Email will be listed under Hide My Email – This App Received.
On Desktop or Laptop:
Sign in to appleid.apple.com.
Go to the Sign-In & Security tab.
Click Sign in with Apple.
Select Vector.
Your Relay Email will be displayed under Hide My Email.