The Windows toolkit must be installed and then loaded to be used.
It can be installed in GNU Octave directly from octave-forge, or can be installed in an off-line mode via a downloaded tarball.
The toolkit must be then be loaded once per each GNU Octave session in order to use its functionality.
If running in Windows, the package may already be installed, to check run:
pkg list windows
Otherwise it can be installed by installing the requirements and then using the online or offline install method.
With an internet connection available, the Windows package can be installed from octave-forge using the following command within GNU Octave:
pkg install -forge windows
The latest released version of the toolkit will be downloaded and installed.