Photoroom supports logging in with your Apple account. If you are unable to log in using your Apple account, first check the basics:
You are using the correct email address for your Apple account
You are using the correct password or a valid sign in key.
If you have the correct email address and password/sign in key, the log in problems may be related to Apple's Hide my email feature. You can work around this by logging in with the relay email address for your Apple account.
To find the relay email address for Photoroom:
On your iPhone or iPad, go to Settings.
Select your name.
Select iCloud.
Make sure Private relay is turned on.
When Private relay is on, select Hide my email.
Look for the relay email address that's used for the Photoroom app.
When you log in to Photoroom, select Continue with Apple and use the relay email address.
Still can't log in? Please contact customer support for assistance.
Related information
Official site: What is Sign in with Apple?
Official site: What is Hide my email?