So this tf2 map workshop is still in beta. For whatever reason, when you subscribe to the addon, it buries the map file in your steam/steamapps/workshop/content/440 folders and the game doesn't seem to read the file from here.

So if you want to do host a solo session to take a look at it before playing it on a server (where it will download to the correct place anyways) you have to take the pl_rocketravine_b5.bsp file and put into Steam\steamapps\common\Team Fortress 2\tf\maps or \Steam\steamapps\common\Team Fortress 2\tf\downloads. After that you can select it from the drop down list of maps from the create server menu or you can just type "map pl_rocketravine_b5" in the console. Doesn't have bot support yet but I plan on trying to implement that in the next version.

I'm not sure if this is some how an issue on my end or a problem with the tf2 map workshop at the moment, but that's the solution I got for right now. Like I said, if you find a server with the map and join it, it will download it automatically for you anyways!