It's pretty good for a first map
Although i dont know anything about how mapping works in assaultcube, i still can give you some recomendations:
-Avoid dead ends.
-Try to not leave too dark places around the map.
-Try to clip windows or other kinds of ways to get stuck out of the map.
Still need some texturing, and something to fill a bit more the map, it feels kinda empty (You could add a road in the middle part, so the lamp posts make more sense) And i don't know... a tunnel, or another building in the wall where that double pistol is. Just giving some examples.
Anyways, it's really nice map, to be a first map. Nice work!