I am looking at images of other people's Action Center in Windows 10 and many of those
show alerts from Facebook.

I upgraded my tablet from 8.1 to 10 last night. I already had the Metro Facebook app installed.
It works fine in Windows 10

When I go into All Settings>System>Notifications & Actions and scroll down to "Show notifications from these apps" Facebook is not an option.

Am I doing something wrong?