Easiest way if you don't already have PHP running on Windows is to download Xampp from:
Pretty easy installation is to download the Zip file and unzip it to c:\xampp in some cases if you unzip the file it will unzip to c:\xampp\xampp you will want to move the files to sit in c:\xampp then open the setup_xampp.bat file and in most cases after that you are ready to turn it on.
You would then open xampp-control.exe and this will allow you to start/stop the various items.
This is not a plug/advertisment for Xampp solely, Xampp is the easiest way to get Group-Office installed and running on Windows that I’ve seen so far. Of course downloading Apache, PHP, and MySQL and installing them correctly should allow Group-Office to work.
Make sure that you update the Group-Office.php file first before you install as you have to change a few things.
File Manager Mod still is not guaranteed to work, at least last time I tried the Mod on windows it didn’t work.
Hope this helps.