Okay, I did a run-around and played on the map with some bots for a bit.
Well, first of all, this happened. Remember to pack your textures (I saw an error model somewhere, too)
Cut down your sightlines!
When you stretch your sightlines out too much, it tends to make snipers woefully overpowered, and just generally makes the map's flow fairly poor. Also, this really screws over engineers, because it makes it next to impossible to build anything, and since the sentry gun's firing radius is only 1100 hammer units, that means anyone can quite easily shoot at the poor defenseless sentry.
I think your sightline issue stems from two major things:
One- the layout is a rectangle, let's be real here. Now, every new mapper does something like this early on, but trust me, your map will be much better if you think of a more interesting layout. (When I was still learning, what I did was I forced myself to make sure as few of my rooms were basic boxes as possible. That's not the best way to do it, but it's a start) Even putting in something as simple as a 90 degree turn after 2nd would help a lot.
Two- Overscaling. You could honestly get away with shrinking the width of this map by 75% and the height by as much as 50%, and it would probably feel a lot better (after you adjust some doorways, obviously). But yeah, overscaling really messes with sightlines bad. Put in a few prop_statics of player models so you get a feel for how big a merc will be while walking around the place.
Moving onto more specific things...
No forward spawns. Why. Whyyyyy. This is honestly the worst thing you could do for the balance of a 5cp map, it makes it so hard to push anywhere past mid. Especially with the aforementioned overscaling.
Mid is a cesspit of spam, snipers, and misery. Put in some proper flanks (you kind of have some, but they honestly do absolutely nothing), more height variation, and most importantly a bit of cover on the point so it's possible to cap without getting headshot immediately. This combined with the lack of forward spawns makes this map incredibly stalemate-y.
Second is... slightly better. There's still no cover on the point, but there at least feels like some semblance of height variation (even if it is just two levels). It's just way too easy to defend. Here's what I would do: Take that pile of dirt you have up against the wall, turn that around, and attach a platform to the back of it, and put the point on that. Add a bit of cover, and whammo, you have a somewhat sensible 2nd point (though it still might be too easy to defend).
I didn't get a chance to play on last, nobody got there. But it looks like a carbon copy of 2nd, just closer to spawn, I can't imagine it would be much fun to play on. Just put something... interesting there. Anything. It's alpha, you can do whatever you want, so put in something weird and inventive as a wild card, and you'll have a good jumping off point.
Oh, and I nearly forgot: Put the actual version of your map in the filename, it makes it easier for people to download updates, and it's also better for archival purposes. It's just generally more helpful.
Anywho, hopefully my giant wall of text helps you out. I'm interested in seeing how you improve the map.
Don't forget you can hop onto the discord server and upload your map if you want to get it actually playtested.FINALLY! criticism, and some pretty good info as well. might do some of these changes when its not much of school work for me alot. other than that thanks!