How it works
On the sign-in or sign-up page, click Login with Google. You are redirected to Google, asked to pick an account, and sent back signed in. If this is your first time, a new account is created using your Google email as the sign-in identity.
One method per account
Accounts do not merge. If you signed up with an email and password and then click Login with Google using the same email, the two are treated as separate accounts — the Google sign-in creates a new account rather than linking to the existing one. Pick one method when you sign up and stick with it.