You might have to check the extraction procedure, because from what I see, it appears those files are cut improperly making it hard to listen to anything due to timings. And from what I've read about the software, it appears that it can create mix compilations with your files and additional effects. I've managed to download a version of SoundTrax and followed the software's instructions, then I replicated the process you've mentioned above and the files play normally on a USB stick. Only one suggestion, avoid using folders. Place the files in the root directory of your USB drive and then play them.