Okay, it's a little confusing, but here's what to do-
go here
https://www.hpcfactor.com/scl/1110/NSBasicCE/NS_Basic/CE/version_6.0
download
NSBasic_CE_v6.exe
install that file, add the serial number 246gt when installing
After installing, go to Program Files/NSBasic/CE/Installers
then install all of the setup files + install cab files for the following as needed, for example, Script, System, MGCE, etc
Then that should get you a working installation I believe