Use the iCalendar URL from your Google Calendar or Outlook/Office365 to have the IoT Calendar service parse your events.

Google Calendar

Hover over to one of the calendars in the "My Calendars" or "Other Calendars" section on the left side pane. Click on the 3 vertical dots at the right of the calendar name, then select "Settings and sharing" option. This will bring up the settings screen for that calendar. Under the "Integrate Calendar" section, choose either the "Secret address in iCal format" or the "Public address in iCal format" if you have made the calendar public (under the "Access Permissions" on the same page).

Outlook / Office365

From Outlook 2016 in the calendar page, right click on the calendar under the "My Calendars" section on the left side pane, then select "Share | Calendar Permissions". A web page will open with the permission settings and HTTP and iCal links. Use the iCal link with the IoT Calendar service. Note you can also set the permissions here to specify the level of details to show in the iCalendar feed.

From Office365, click the gear icon in the upper right corner of the screen, and select the "Calendar" option under the "Your app settings" item. Under options menu on the left pane, click the "Calendar | Shared Calendars | Calendar Publishing" option. Use the iCal link as mentioned above for Outlook.