Don't know why I got this DLC, gave it a try yesterday and it's very meh, it's feels rough around the edges, I expected a bit more quality and polish from Colossal / Paradox.
For 10 euros more you can get an entire simairport game by the same name by an indie dev, skip this DLC, forget it exists and if you want to scratch that airplane itch/urge then just buy the game I mentioned.
It makes me miss the simple yet functional airport system we had before.