As far as the 2016 situation, here's the gist:
2016 model year C-Maxes with the appropriate trims/options (ie: Has the 8" touch screen, not the 4" non-touch unit) would have been supplied with Sync 3 vs Sync 2. But the USB hubs in the center console were not compatible with CarPlay. I believe something to do with a special identification chip that Apple requires. Don't quote me on that though. Android Auto users don't have the same issue. But 2017+ model years they updated the hub so it is compatible.
There was also a software update to Sync that was needed too. Many may already be past this. Always recommend to go through Ford for these updates first and it'll get the software side sorted out: https://www.ford.com/support/sync-maps-updates/ . Some suggest using Cyanlabs to get to newer 3.4 versions that Ford doesn't officially support on our vehicles but it requires some technical experience and has the potential to brick your APIM.
If you happen to still have an older hub and update Sync 3 to the latest available version to you, you should then receive a warning on startup about USB hubs not being supported.
The hub replacement is inexpensive and quick to do. The hub in the center console just snaps in. Pop it out, there's two connectors on the back. Unplug the old, plug in the new, pop it back in. No further work or programming needed.