It is always best to sign in with Google, Microsoft or Apple sign-in. This eliminates the need for passwords and email verification.
If you'd rather use a password you first need to click Login then choose "sign up" at the bottom of the login form.
You only need to do this once.
Provide your email, choose a password then click sign up. You will be send a verification email. Click the link in the email and you can now sign in using the email address and password you just chose.