Installing Virto Office 365 Calendar Add-In
Before you begin, you have to make sure you have access to the server and your account must have the appropriate administrative privileges to install applications.
When Office365 Calendar Add-In is installed, it is automatically added to your site on page Site Contents.
To adjust Calendar view for SharePoint list, you have to define data source settings first of all. Click on Office 365 Calendar Add-In icon and open default calendar, and then go to a configuration page for data sources.