In the Extension Modules section, under Connections to external services, we also find a link to Google Calendar. Clicking on this module will display basic information about the module, the price per user per month, and the total amount for all users per month.
By clicking on green Buy module button and subsequent confirmation will make the module active.
Then we go back and click on the Google Calendar module, where we will see two options - Manage the module and deactivate it. In this case, we click on the green Manage module button:
We will move directly to the Google Calendar settings, where we will define a time window for downloading older events: 
The final step is to set up a Google Calendar connection with a specific user account in CRM Mango. Go to Settings -> My Settings -> Google Calendar Connection:
In the last step, the user selects their Google account and the connection is complete.