I really liked this plugin, but it quit working a while ago.
So, here's a substitute. First, install either Jetpack or Shortpack so you have the [audio] shortcode available.
Second, install my new plugin called MMWW. MMWW will read the metadata from your MP3 files as you upload them, and provide an "Audio Player" button to let you create the appropriate [audio] tag.
I'm very grateful to the author of this plugin for idea and the example code.