This post was split from topic:
I am having this issue. I have tried private windows, made sure there is not trailing spaces. I have 40+ WPForms Apps. This one is giving me a hard time.
We hit an error adding your new account
authentication failed: The app returned "403".
- Make sure you click "Allow" or "Accept" on the permission popup
- Double check your Account has the correct permissions
- Check out our help docs for more information