You'll need `ffplay` from [FFmpeg](https://ffmpeg.org/) to actually play music. On macOS, `ffplay` is part of the Homebrew ffmpeg package, but you need to build it with `brew install ffmpeg --with-sdl2`.
Use `pipenv install --dev` from [Pipenv](https://docs.pipenv.org/) to install the Python dependencies and set up the package with a `stream` executable.