Have you installed the X-Plane plugins? In contrast to MSFS, X-Plane requires a few more installation steps than just starting the Simlink application.
Close X-Plane
Open Simlink
Press “Plugin status”
Press “Plugin settings”
Press “Scan & install”
Make sure that your simulator is showing up in the list with a green checkmark
See this post for images of each step along with an additional manual approach!
That should be all you need to get moving maps going in X-Plane 12!