Install AUR.AUR from the
For running JDownloader you need Java installed. OpenJDK is recommended, it works flawlessly with jDownloader.
Use the command jdownloader to start JDownloader. When you just installed JDownloader from AUR, this will run the update tool to download some required files for JDownloader, else this will start JDownloader directly.
When you first start JDownloader you can choose your preferred language and also your download directory. On the next window, JDownloader asks you if you want to install FlashGot, a Firefox extension. I recommend clicking on Cancel. If you want this extension, you can still download it through the official mozilla addons website.
If you enable the Light(GTK) theme and the fonts appear to lack anti-aliasing, modify
~/.bashrc as appropriate following the directions here.
Tips and tricks
Downloading files without creating a subdirectory
By default jdownloader will create a subdirectory for each file you download in your destination folder. To stop this behaviour go to Settings > Packagiser and untick the predefined rules as desired.
Changing preferences for individual sites
Preferences for individual sites can be found by going to Settings > Plugins. For example, by changing settings on the youtube.com plugin you could tell jdownloader to only download the audio from youtube links.