Leave the "Application Type" set to "Web application"
Under "Authorized Javascript Origins" enter: https://<the.host.domain>
Under "Authorized Redirect URL" enter: https://<the.host.domain>/auth/callback/google
Click "Create Client ID"
Under "APIs & Auth", click "Consent screen"
Enter your/an email address, Product Name, click "Save". What you enter here will appear on the Google OAuth pages when authenticating.
What about first Login?
visit "https://the.host.domain", do the oauth dance and then visit "https://the.host.domain/en-US/account/logout" and enter the default admin user/password so you can log into the UI and setup your users.