It's not possible to download/export content from Spotify using the API. You can download music from Spotify on your personal devices with the official apps. Any other ways aren't supported and might not be in line with the Terms and Conditions of Use.
You can integrate your app with the Web Playback SDK so Spotify users with a supported browser can listen to music on your website.
Let me know if you have any questions!
Have a great day,
HuboRock Star 16
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