Path: Settings > Configuration > Social Authentication
To use the Google Single Sign On / Social Authentication Google, you need an OAuth 2.0 client ID, which your application uses when requesting an OAuth 2.0 access token.
To create an OAuth 2.0 client ID in the console:
1.) Go to the Cloud Platform Console.
2.) Go to the three dots at the top right and click on "Project Settings"
3.) Create a New Project
4.) Name your Project
5.) If the APIs & services page isn't already open, open the console left side menu and select APIs & services.
6.) Click New Credentials, then select OAuth client ID.
If this is your first time creating a client ID, you can also configure your consent screen by clicking Consent Screen.
(The following procedure explains how to set up the Consent screen.) You won't be prompted to configure the consent screen after you do it the first time.
7.) Click Web application
7.) Click Create client ID
8.) Go back to your website. And Copy and Paste your Client ID and Client Secret into the site's settings under "Settings", "Configuration," scroll down to "Social Authentication Settings"
TIP: If you are a Gsuite Admin, please make sure Google Developer Console is enabled.
https://admin.google.com > Apps > Additional Google Services > Google Developer Console Enabled.