Found the answer in the readme:
Some Windows users have observed that the install fails due to an incompatibility between the installer code and Windows Server 2012 R2 or Windows 8.1.
To avoid this, run the installer (Setup.exe) in
compatibility mode (compatible with Windows 7 or 8) as
follows:
1. Display the directory to which the package has been
unpacked in Windows Explorer,
2. Right click on the Setup.exe icon and select
properties and then the Compatibility tab
3. Select "Run this program in compatibility mode for"
and "Windows 8" in the drop down box.
I doubt that it is 'some' and should be noted on the install page