:-(, I thought this was gonna be the real deal Machine Learning shizzles, but turns out its a wrapper around a paid API :-(
Open-washing seems to be more and more of a thing lately -- make an open (which is usually confused for "free") source SDK/client for your closed-source SDK, get the PR and maybe even some contributions.
That said, they've given people a nice base to replace the bit that deals with their API with some other API, not that I'd do it but it's at least possible.
This is not an "open source Shazam". It is an open source interface to a closed product. I'm not flagging it because maybe someone finds it useful for something, but the description is simply misleading.