Display calendars from supported MISs or third parties in Firefly.
Configure your Office 365 calendar so that you can display it in Firefly.
Pull your MIS calendar through to Firefly so that it can be displayed on any page.
Configure your iCal calendar so you can add it to a Firefly page.
Firefly has built-in functionality for Exchange calendars, however, every school which makes use of this is currently hosted locally.