Quick link to latest release: latest release.
Source Code Access
The Git repository is hosted on GitHub.
The default package includes the source code needed to use the library. If you're not sure what you need, get this.
The source package includes build files and tests. You probably don't need this unless you want to do development on the library or run the tests.
PHP MIDI Library is released under the WTFPL. That means you can whatever you want, whenever you want, however you want. It's freedom without confusion or limitation.
See the quick start guide for information on getting started using the PHP MIDI Library.