It looks like we haven't got music file upload features just yet at Piano Tell. Flarum sites do support music file uploads, but most likely hasn't been activated here, or not enabled. But that's ok - external linking can be used - but maybe not as reliable, because we know that files at some external sites can change, or external sites can go down, or even disappear altogether.
Will put up my Pirates one for testing.
I have a WAV file link, and a FLAC file link. The flac file can be three times smaller than the wav file, and flac audio is also lossless.
Flac - pirates - flac - 2.7 MB
Wav - pirates - wav - 8.3 MB