Cant get this library to work - launchpad libarary

I’ve been trying forever to get this launchpad library to work with processing. I’ve looked everywhere for any info on how to get it to work but I just can’t find anything. The library seems to be made for an older version of processing, yet when I try to run it in the oldest version I can find (1.5.1) It still wont work. It always gives me this error:
“the package com.rngtng does not exist, you might be missing a library”
I followed the install instructions carefully and the library is in the sketchbooks library folder, so I’m not sure what to do.
One thing I’ve found is that there needs to be a folder called “library” in the library folder that contains a jar file, but I can’t find it.
Here’s the library:
Does anyone know what might be going on?

Were you able to resolve your problem, @Brastin?

If not: what specific operating system and PDE version(s) are you working on, and can you provide simple sketch code that you are using for testing?