That looks as though the setup.py script didn't manage to install all the dependencies properly. Firstly I'd try running python setup.py install from inside the Showtime-Live-1.3 directory to try grabbing the server dependencies again. Let me know if you encounter any error messages during this step.
If that doesn't fix the problem and you're running Python 2.7.9 or higher, then try running C:\Python27\Tools\Scripts\win_add2path.py to add the Python scripts location to your path variable.
After that, try running pip install zeroconf in order to fix the dependencies for zeroconf. I also recommend running pip install netifaces to verify that zeroconf's dependencies installed correctly. You should now be able to run LiveShowtimeClient.py from any command prompt or the Windows run prompt (Windows key + R, LiveShowtimeClient.py).
Sorry about the hassle, the Ableton Live to Unity server is still quite experimental and it's currently my top priority to make it easier to install and use than the current system. Let me know if this fix works for you!