Thanks for reaching out. Spotify works hard to have all your favorite tunes. However, some tracks and artists aren't currently available. I'd recommend checking out this Support article for more info.
Sometimes the artists haven't uploaded their music to Spotify. You can encourage your favorite artists to do this so you can stream their songs. You can also download the tracks and stream them as local files on Spotify. You can learn how to do this in the image below.
Hope this works and have a nice day 🙂
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