okay i might be late but for anyone who doesnt know here's the way to download:
first you need to subscribe to this map you will see that its downloading the map

second go to your folder towards Local Disk C:/Steam/steamapps/workshop and you will find to go towards downloads, head towards a folder called 440 and you'll find a folder with numbers head towards one and you'll find the maps name if its not in downloads go to the folder "content"
third what you're going to do with that bsp (they're called bsp's), is to get out to workshop and go to common head towards team fortress 2 go to tf and go to maps thats where you will put the bsp.