Ah, so you just want to download free music?
Hope you don't mind my saying this but you're making it more complicated than it needs to be for your father. My advice?
Get him a dedicated internet radio. Preferably one that comes with options (most do) like regular FM radio, a USB port, bluetooth, lit display, etc. But it sounds as if all he needs is
a device to play cajun music stations.
Try
this link for a list of some of the best on the market now, but amazon has plenty of them.
Otherwise, you're going to limit your pop to mere playlists when with an actual device he can get up to 30,000 internet stations and also have the option of using a stick. But from my experience most older people can't be bothered with "extra gadgets". They just want their single source and be done with it. Good luck.