导出ics文件到php中的google，apple和outlook日历

Question

I want to export the *.ics file to Google, Apple and Outlook calendar. I am using following urls to export the file but its giving me issue for some urls. Following are the details.

For Google export *.ics I am using url. https://www.google.com/calendar/render?cid=https://www.google.com/calendar/ical/rossmontessori.org_2gbp51hggdr1j6rstfho88iqls%40group.calendar.google.com/private-407f2123de0296b5c886167f48d9a4a7/basic.ics

For Apple and Outlook https://www.google.com/calendar/render?cid=https://www.google.com/calendar/ical/rossmontessori.org_2gbp51hggdr1j6rstfho88iqls%40group.calendar.google.com/private-407f2123de0296b5c886167f48d9a4a7/basic.ics

Its working fine for Apple and Outlook but giving error message for google calendar.

Error message:

Cannot add calendar "Hot Lunch" You do not have access to Hot Lunch's calendar

Any one please help me for this one?

Thanks