What can I do with an MAA official?

I recently entered the Expansion Phase and received my first MAA official. However, as far as I can tell, there is nothing I can assign them to? Also, one of the hints says to select Settlement and then MAA, but no such menu item exists.

I can see total settled area from the Expansion Phase goals tab, but I don't understand how I'm supposed to increase "land assigned by MAA".