Anna is the type of person to try and skirt the rules, and also follow the path of least resistance. Most likely she got the citadel just by stealing it, and acquired the demons because they're weak and easy enough to dominate, and she just managed to do so in large numbers.

A long while ago I played a very simple trading-based space video game (don't remember what it's called) that tried to focus players on acquiring bigger and better things. I violated that principle by instead finding a quiet corner with a planet in it, and built up wealth and resources quickly until I basically controlled the entire sector. Even the game-controlled drone patrols couldn't beat mine.

Now imagine Anna could do the same thing, only she knows every possible hack for the game, so she could do so much faster.