Are any of them custom/local file songs? In order for others to be able to listen to the playlist, you would need to add songs from the Spotify library to the playlist instead of local files.
If the local files are not in the Spotify library, they cannot be added to a Spotify playlist and shared with others. However, there are a few workarounds that you can try:
Keep in mind that these workarounds may not work for copyrighted music and could be illegal.
As you mentioned you were trying to create a playlist, here's a couple playlists I think you may be interested in that you could also share:
Even if you have local files, I believe only those should just not show up to others.
Does the playlist work for you? Can you see all the songs in it?
If yes, please make sure your playlist is set as a public playlist.
If you see the highlighted button, your playlist is public.
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