Install Octave for windows (free):
1) Navigate to: https://ftp.gnu.org/gnu/octave/windows/
2) Download and install latest octave-installer.exe
3) You can permanently modify the path Octave searches by editing the file:
C:/
Octave/Octave-X.X.X/share/octave/X.X.X/m/startup/octaverc
as explained here