Hi Stephanie G,
Just curious...Maybe the problem is with your local machine and how it handles '.ics' files. Try sending a test email to your smart phone (and/or a colleague's computer) and clicking the link there. It should then open your calendar app if it is a properly-formatted '.ics' file.
If it continues to open as text, you may want to examine how you are outputting your ics file. I personally create the event in my outlook calendar, then 'save as' to another location and name the '.ics' file using the unique identifier my webinar app assigns to the event: xxxxxxx.ics. That way, once I've created a TOKEN with that event identifier in it (in the program,) I can reference all of these event-specific assets in emails, landing pages, etc. and manage them more efficiently.
Hope that helps,
Mark F.