Is it possible to add a Sharepoint calendar to eM Client? I do have a pro Account, FWIW.
If they support CalDAV then it can be done by going to Menu > Tools > Accounts and adding a new account. Choose Calendar > CalDAV.
If SharePoint supports iCalendar sharing, then you can add it as a read-only calendar. Choose Menu > Tools > Subscribe to Internet Calendar.
Otherwise if you have a Google Calendar, I believe they have an API to link to SharePoint.