When creating an Invitation Email, you will have the option to attach a .ics (calendar) file to it.
Quick tip: calendar (or .ics) files can be used so that participants can easily import meeting dates/times into their calendars in applications such as Outlook or Google Calendar.
To attach a .ics file, go to Advanced options (either when you create a new Meeting or edit a Meeting) and click on Schedule.
At the bottom, after the field Agenda, you will have the option to either attach, not attach or add a link to the calendar file.
Once you have made changes, remember to save them by clicking the red Save button on the bottom-right of your screen.