I have been having trouble getting WAB Dev to work on my Mac. I've installed Node.js (4.2.2) and run node server.js in my terminal and when I go to the localhost it doesn't work. I've done a search and haven't found much about others having trouble with OS X and WAB Dev. I have a feeling it's related to node server.js. Any Ideas. I don't have a screen capture of my terminal, but I will add it tonight when I get home.
Have you made sure you have the correct port (http://localhost:XXXX? I can't remember which it is at the moment but it's in the docs. I had no problem using WAB on a Mac.