Yield

Hey there!

Welcome! I'm glad to see you've started with a 5CP for your first map, and it's nice to see such a good blank slate. From my walkthrough there's some neat ideas and some very, very blank spaces.

1: Everything feels overscaled, specifically the size of most of the rooms and arenas. The doors are totally dwarfed by most of your walls, both in length and height. If nothing else, think of some ways to break the open spaces up. While some of those spaces server a purpose, so you can break them up later with visuals, I think you'll have more success if you break them up now with geometry. Small vertical components, like ledges, or just making some of the areas closed off, like with sheds or buildings, will go a long way to filling out the map.
2: Don't worry about lighting yet, at all. Alpha lighting doesn't matter beyond having it (not fullbright). To be honest the lights I did notice were all very very bright, though.
3: The design is very simple, which means it will play easily, and people will get it. Making a 5CP that isn't just a rehash of Granary out of this kind of shell, though, is very hard. I don't know if you've played cp_follower before, but I use that as an example of a map that borrows the same feel of "square areas carved out of a long rectangle". This map has that same flavor, but (almost) none of the interesting verticals that Granary has. The vertical element that I did like was the ramp leading into 2nd (left side). The rest of your verticality seems very... out of touch. The higher level at mid feels like another battlefield entirely, plus the mid CP is way too cramped. At least remove the glass roof at middle, to make that upper path useful. Also, I'd suggest removing the rails on top and adding some sort of additional level of height, either lower than the ground or higher than the balcony, to spice things up. It all depends on what sort of theme you want to go for and what concept you're going to apply, but say if this were a desert themed map, like Badlands, you could go with something similar to the Spire on 2nd/4th there. You know? Think of some ways to add interest.
4: Just some notes: The rocks at middle are strangely placed on the ground so that they get wider and then taper off; just lower them like 32 units to fix the weird shape they make. The stairs in the room at mid are like... 18 unit steps? They're huge. Make smaller steps or else people will be afraid to try and use them. The pathway to last is too linear. That room between 2nd & Last will ALWAYS end in a stalemate, because there's basically only one pathway for either team to go through. Think about how on Granary there's the left and right doors, separated by a wall so they can't both be covered at once, and then the upper level, completely separate and flanky.

Good luck, I love to see 5CPs! >:3

-FoX

Yep. Steps are rise 8 run 12.

A few notes I'd make.
First, like FoX said, some things feel overscaled. The stairs, especially, I might note, seem to have railings that are unusually wide. Similarly, a few textures seem ill fitting- that is to say, that the chicken wire below the stairs has holes big enough to fit a chicken through (a rubber one, at least), and the glass with the crosses above the central control point seems rather too busy, though this may be due more to the compounding nature of a grid above another grid than the texture scale.
Second of all, the second control point is easy to miss. Most people don't look behind them often, so it's all too easy to run past the second point to the last one. Putting in more arrows than you think that you should need could help alleviate this issue.
The third and final thing I'd like to point out is something more aesthetic than anything else. That is to say that, the central control point seems rather off center.
Beyond this, it'll be hard to say what needs to be done. More props, more details, and more players would be in order if I were to try to figure that out. You might want to sign up for a game day, for the players.