The ICAL feed is an export format you can use to subscribe (or to let other people subscribe) to date-and-time-based data in a calendar application or web site such as iCal, Mozilla Calendar or Google Calendar.

The ICAL feed option only appears if you have a column in your view containing Date and time values. (This will be self-evident if you can access the Calendar view.)

It is also only available for permanent exports from saved views.

If you want any export to be available to someone (or to a service like Google Calendar) without a Dabble account, you need to ensure that you have enabled Allow public access to exports in the Sharing preferences for the application.