Hi, I wanted to check your map since you didnt post any screenshots in the download thread, and I think there is a few things you should fix:
Starting with the name file of the map, you should add always the version of the map as a sufix, for example koth_grgstation_a3 would be the next version. Not only makes it easy to know the state of the map to players, but also I think if you reuse the same name over and over the bot of the server goes nuts and dont play your map. Here is a video if you want to know more about it:
View: https://www.youtube.com/watch?v=m7YqJ4MyG7w
The next is the map itself, it's too small for a KOTH, it's even small for an ARENA, and everything is too cramped. This spawn is too small, you have to keep in mind that 12 players have to fit here. And have multiple exists to avoid spawncamping.
I recommend you to check other KOTH maps to see the sizes they use. Here is a thread with a bunch of decompiled TF2 maps:
Badlands • Byre • Granary • Graveyard Lumberyard • Nucleus • Offblast • Perks Ravine • Sawmill • Watchtower • Well Altitude • Brew • Carrier • Coal Pit DeGroot Keep • Dustbowl • Egypt • Erebus Frostwatch • Gorge • Gorge Event • Gravel Pit Hardwood • Junction • Lava Pit • Mann Manor Mercenary...
tf2maps.net
Another thing you wan to avoid is empty spaces. In maps there is usually props or brushes to prevent sightlines like this one
Also the map is a bit dark, i recommend checking a prefab i did with every environment setting in tf2:
This is a collection of all the official environments. I'm aware that this was made before, but I think all of them are outdated by now, so this one will be updated with every new map. Also it includes TFC and SFM maps. If there is a mistake...
tf2maps.net
The control point, is too cramped too, but it also has the issue of not knowing where is the capture zone exactly, put some overlays to make it clear.
Also the capture time I think is too long, reduce it to 8 seconds. And for the last nitpick, clip the stairs with a blockbullet.
Overall, for your first map its decent, my first map was way worse than this. You mostly need to look other tf2 maps as a reference and size the sizes they usually use. You should put your map in the server to be playetested and get feedback, it's how maps get improved. Also, i dont recommend posting your map in the tf2 workshop until is finished. So keep working on it!