What version of MacOS X do you run (look under Apple-Symbol -> About this Mac)?
There are two different drivers for different versions of MacOS X.
You can run it from 10.9 (Mavericks) to 10.15 (Catalina).
If you have an old MacBook Pro that cannot run 10.9 or later it won’t work. Alex tried to make it compatible with 10.8 but it didn’t work.
Another reason why it might not work on older machines is that they only run a 32-Bit software OS and SoundJack is 64-Bit only (at least on Mac and Windows). So it does not run on 32-Bit Windows either.
It runs well on my MacBook Pro 4,1 (early 2008) and should also run on a MacBook Pro 3,1 (late 2007), but probably not on earlier MacBook Pros.