Mmmm, check your ports, should works on 27015 port.
You should run the game, then run the tool from the host (LAN) executable, set the server, other should run the Client executable. Thats in theory and that I understand as my chinese is not good.

Now, Author says that after version 1.3 (current version is 1.4a) his frontend would not work without steam and if thats true, probably his frontend does check if steam is running, but still worth trying if this will work with revemu or offline mode as well, if not working, letting steam on to play free game with friends is just silly.
Anyway, I can't play the game at any decent frames on that pc but will be enough testing it, when I'm done here, will shoot you pm.