Your link is missing some part. Past it like a URL so we can get it right.
Anyway, it sounds like your problem has to be this:
"Categorise audio files correctly
It is important to organise audio files appropriately, because audio files in the Sounds project folder are downloaded completely before playing, but files in the Music folder are streamed. This means if a Music track is accidentally put in the Sounds folder, it would have to download completely (which could take a couple of minutes) before it started playing. However, audio in the Music folder can start playing immediately since it is streamed from the server."
https://www.scirra.com/manual/109/audio