Supported Calendar Accounts on the Invisible Smart Display

Google Calendar

Google Calendars are natively supported. You can directly connect to and sync with a Google account. The configuration is done via the companion app

Outlook Calendar (Microsoft) 

You can use the "publish" feature in outlook to create an ICS link for your outlook calendar. With this link, you can then add the Outlook calendar to the Smart Display via the companion app.

Note: The URL or a "public" Outlook calendar is secret and hard to guess, but there may be situations where this isn't as safe as a password-protected link. So you will have to use this option at your own discretion. 

Instructions can be found here

iCloud Calendar (Apple) 

You can "publish" any iCloud calendar to generate an ICS link. With this link, you can then add the Outlook calendar to the Smart Display via the companion app.

The URL of the ICS link is hard to guess, but there may be situations where this isn't as safe as a password-protected link. 

There is a relatively simple but unofficial way to obtain a more protected ICS link.

You may find the necessary instructions on this external website: https://www.techrepublic.com/article/how-to-find-your-icloud-calendar-url/