I did exactly like instructions but it didn't work but on Windows 7 it worked im gonna try again with a fresh install of Win 10 Ghost Spectre SuperLite v1909
I honestly tell you that I only install complete and clean stock versions, since then problems come and you don't know why they originated.
I have tested this program in Windows 10 Pro 1909 updated and it works.
Just in case, check if port 9999 is not being used by another application (it is difficult, but not impossible).
In CMD or PowerShell enter the command
netstat -a
and look in the column "Local address", the number after the colon to the right of the IP will be that of the open port on that connection.
To end the execution you can press the Ctrl - C keys or close console.