Thanks for providing the free version, it allowed me to get it working in Linux before buying. The process itself is fairly straightforward:
1) Download and unzip the windows version
2) Delete everything but www and package.json from the folder you extracted to
3) Go to https://nwjs.io/ and download the linux version.
4) Unzip to the folder with the www and package.json you kept previously in.
5) Create a /save folder (not a relative path) and have your user be the owner eg. `sudo mkdir /save` followed by `sudo chown [user name here] /save` remembering to replace [user name here] with your actual user name
That last step isn't ideal, but required if you want to be able to save.
Not had any issues with this so far but I don't think I'm all that far in either.