Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
It's the same on any OS. Download the installer from the download page, run it with java, follow the instructions
If you're using the installer it will be named "Aristois-Free.jar". You run this file with Java. If you're using the manual zip file it will be named "1.19.3-Aristois.zip". Can you send a screenshot of the contents of the "1" folder?