Sorry to hear you’re having troubles. From the steps you’ve listed it looks like you’re doing the right thing, but there must be something that isn’t quite right.
The main things to check (even though it looks OK from your description) are:
Make sure the folder you’ve copied the file to is under /Library and not ~/Library (both will likely exist)
Make sure you copy the .jar file directly under Drivers.
Sample terminal output of a correctly placed driver file: