Yes I forgot that the Music app will find the files anywhere they are. Just be aware that (at least from my test) the mp3 files are not in the music folder (but I guess that makes no difference anyway) so enjoy listening.
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Install Amazon Music app launch it and login and go to the Purchased tab. There you see right on top a download icon. Clicking that will download the entire purchased library. you can also choose each song individually. Amazon will create a folder structure using numbers and names in /storage/<somenumbers>/Android/media/com.amazon.mp3/ Since Amazon does not copy those mp3s into your music folder the best way to find where they are is to use the My Files app to search for one of the songs by name. That will show you the path to the location of the entire library of songs that got downloaded. Move these MP3s to your music folder and enjoy. Sadly I think all mp3 files with have a prefix added to their name (at least in my case it was). Cheers
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