When one creates a Go To Meeting meeting, they have an option to add that meeting to their calendar. Currently clicking on the add to calendar link downloads an .ics file. While this works for PC based calendars, it does not work for cloud based calendars.
The work around support suggests is to use a PC base calendar and then sync that with your cloud calendar. This is a bad solution for the following reasons:
You are forcing a clumsy solution that requires setup 3rd party tools.
It is prone to break if a Windows 10 update updates Mail and Calendar applications
The Windows 10 Mail and Calendar tools do not use modern authentication methods.
This does not work if a users is using a MAC or Chromebook or mobile device.
There is another way to add an .ics file to a Google calendar, but it is a multi step process that most people won't do even if they know how to do it.
Both of these solutions are high friction and push the burden of bad web design on to your end users. Many of your competitors have a way for a web page to add an event to a Google Calendar from a link on their page. It is not rocket science, it is not something new, it isn't even something hard to do.