This won't fix all your problems, but I found discrepancies in the first three filenames compared to the names of the files downloaded from the site you mentioned. These will cause load or download errors when your code is run.

'Burn The World Waltz.mp3' // Rename the downloaded file to remove the space before .mp3

'Le Grand Chase.mp3' // Removed the e from end of Grand to match download

'Mesmerizing Galaxy Loop.mp3' // Appended " Loop" to match download