Q: How do you sync Mac Pro Calendar to other devices

Sync-ing calendars in more complicated than assumed.

To Sync a calendar, that calendar  must be stored at an Internet-accessible location. If you have Apple devices, the natural location is iCloud.

You must have your sync-able calendar stored at iCloud, then you need to grant access to other Users on that Server, by configuring it (easiest on your Mac) so that others have the right to see it.