It does work for me. Though it didn't in the beginning.
Try dropping your audio file in this directory "/wp-content/plugins/the-stiz-audio-for-woocommerce/server/myfile.mp3", instead of uploading the file using the admin preview file's path thing.
Then just type "myfile.mp3" (the name of your file) into the preview file path field.
It does work for me. Spread the word, this is a great plugin and many people just don't like it because they haven't seen it working. It's dope.