How to enable Google Calendar integration
You can configure the Google Calendar integration in the Preferences panel in the section External apps. You can enable it by pressing the Enabled button near to it.
You will be redirected to an Google dialog when you will be asked if you authorize the integration. If you do so, you will be redirected to zendone with the integration enabled. Once you enable the integration, it might take a few minutes to have Zendone synced with Google Calendar.