If you want to enable users/agents to log in with their Google account credentials, you should use the Deskpro Google+ Sign-In app.
Google Authentication is an older app which relies on an old system which Google has now withdrawn. If you are still using this app on your helpdesk, you should switch over to Google+ Sign-In as soon as possible.
Deskpro On-Premise users: before installing Google+ Sign-In, you must update your helpdesk to the latest version to avoid a possible issue which will prevent users from logging in.
To configure Google+ Sign-In:
In Deskpro, go to Admin > Agents > Auth & SSO or CRM > Auth & SSO, depending on whether you want Google+ sign-in for agents or users.
Click on the Google+ Sign-In app.
Log in to a Google account and go to the Google Developers Console athttps://console.developers.google.com
Click Create Project and enter a name and ID.
This project will only be used to obtain OAuth 2.0 credentials.
Follow Google’s instructions for Setting up OAuth 2.0, including customizing the user consent screen.
In Deskpro, enter the Client ID and Client Secret from step 3.
Set the Google Apps domain if the Google account you are using is a Google Apps account, and you only want to allow login from Google Apps accounts on the same domain.
If you install Google+ authentication for agents, and don’t set a Google Apps domain, anyone with a Google account will be able to log in to your helpdesk as an agent.
(Agent authentication only) Set the Auto agent option. This controls which permissions are granted to agents who log in through OneLogin and don’t have an existing Deskpro account.
(User authentication only) Set the Grant usergroup option. This controls the usergroup granted to users who log in through OneLogin and don’t have an existing DeskPRO account.
Click Install app.
Deskpro will show you the redirect URI to enter into the project you created. Go back to the Developers Console, and under the APIs & auth section, select the Credentials and then Edit settings to enter the correct redirect URI.
Click Save and Google authentication is now enabled.
If you want to enable Google+ login for both users and agents, install the Google+ app again in CRM/Agents.