Why is the NSX RSU software, not working on Windows 10?

The RSU software is not designed to work on Windows 8/10. The recommended software to use instead is Ecoreach.

The latest version of the Ecoreach software is 2.5 and can be downloaded from here - http://www.schneider-electric.com/en/download/range/62980-Ecoreach/

If the RSU software needs to be used a Virtual Machine could be run with software (VMWare, VirtualBox, Virtual PC, etc) and using Windows 7 or earlier.