help with library downloading

hello,
I came to Github not long time ago although i take around in Github starting guide but still there are somethings i dont get. one of these i found some librires with downloa link while other dont
like this one .
i don`t understand why and i need to download this one.
Thanks for your time 

You need to download the entire repository (available at https://github.com/RobTillaart/Arduino).