You can simply connect third-party calendars by adding them to Apple’s default Calendar App. Just open the default calendar, go to the menu and select “Add Account…” and select your account. After adding your calendar account there, you can close Apple’s calendar app and don’t have to use it anymore if you don’t want to, your account is automatically registered with Meeter now and you will see your upcoming events in the menu bar!
For more information on how to do this, see Apple’s official support page
For simple walk-throughs on how to do this, see our support page