I managed to get this to work, by downloading the NFA KEY zip files on windows PC. Did the extraction, executed the application . It loaded Chrome browser which auto nivigated to netflix page, to which i put in my username and password. Chrome closed, and key was generated in same folder as application. It popped up with a PIN.
It failed a couple of time, but the application finally managed to generate the key.
Used windows explorer to browse to folders on Libreelec. After checking samba was activated on Libreelec settings.
COpied key to a folder.
Started netflix... used key option, then browse to where i saved key.
selected file and was prompted for the PIN...
Only question i have... will this affect other user in my house?
Since now my Pi3 is using the key method, will users having other media boxes with Netflix preinstalled no also be forced to use this key method?