I sign up using the option “continue using Google”, and I tried to find a spot where I can establish a password for my account, but I couldn’t. I tried to change my password using ‘forgot password,’ but after creating a new password, I received the following error message:
You tried signing in as “firstname.lastname@example.org” using a password, which is not the authentication method you used during sign-up. Try again using the authentication method you used during sign up. (error=identity_provider_mismatch)
this is because you don’t have a password when you use the single sign on because the authentication is handled by your google account.
Single sign-on (SSO) is a technology which combines several different application login screens into one. With SSO, a user only has to enter their login credentials (username, password, etc.) one time on a single page to access all of their SaaS applications.
Taken from What is SSO? | How single sign-on works | Cloudflare