Hey man, I just had a walk around your map, some feedback:
First of all, well done on the lighting! Most starters forget to do proper lighting and just go around with fullbright maps, but your lights are very well done and the map seems illuminated greatly in all spaces.
I like the layout so far, map feels quite clean and easy to navigate. You've already got a little bit of vertical areas (like the balcony above A). You could see if you can make the map a bit more diverse with high and low areas.
Overal I feel you've got a very strong starting point here! You've blocked out a strong layout already and I think you should start experimenting with cover and diverse areas and flank routes next. Some other things I'd suggest:
Add another room in here for the actual BLU spawn so RED can't shoot into BLU's spawn and spawnkill everyone.
Add some cover (small buildings, fences, rocks) in between here and the RED base to block off sightlines a bit.
I'd try lowering the balcony walls here to allow sentries to shoot down the ledge; they're currently too high to shoot over while not standing on the wall itself.
This door reversing directions surprised me - it's a fun gimmick but as BLU I still expected it to be one-way. Maybe add some kind of sign showing that the direction has changed? Alternatively, you could add another door somewhere to the left that unlocks when the point is capped, and lock this one.
Hope this helps! Good start for sure, keep it up!
PS: might want to add some screenshots to your download here.