There are no special requirements or additional software needed for k2pdfopt. All I can think is that you have some incompatible software (most likely antivirus software?) that prevents it from running. Perhaps even Windows itself--see
a few posts earlier where you have to tell Windows to allow the software to run. This is because I don't properly "sign" the compiled exe per commercial standards. I haven't figured out a FOSS way to do that which I consider painless enough to adopt.