How to configure Google Extension for Synchronization?

When you open Google Extension in Vtiger - it demands Signin with Google. Make note of redirect_url presented in the Info box (which is bound to your setup).

1. You need to create and configure OAuth 2.0 (refer Google Documentation)
2. Under this Project settings, enable (Calendar API (mandatory) and Contacts API (optional)).
3. Now proceed to create credentials for OAuth client Id (Web Application) type.
4. Copy "redirect_url" you noted as one of the Authorized redirect uris
5. Save the project.
6. You will be prompted with OAuth2.0 Client ID and Secret. This need to be updated back in your installation (modules/Google/connectors/Config.php)

Now proceed with Signin as Google. Authorize the account to which synchronization should be setup against with preferred directions.

Next - Sync Now will get your CRM and Google work together.