I look at your instructions for subscribing to a Google Calendar (https://confluence.atlassian.com/display/TEAMCAL/Subscribing+to+Google+Calendars+From+Confluence). However, these instructions only work for private Google accounts.

I am trying to subscribe to a Calendar that's part of the Google Apps domain. There is no "Private" option there. So I shared the calendar with the public and used the ICAL Calendar Address URL.

I add it to the Team Calendar and it doesn't give me any errors but it also doesn't show any of the events. With or without a username and password, though I shouldn't need one since it's not the "private" url.