Have you recently allowed a website access to your Apple Music and have since changed your mind?
This happened to me. I wanted to use playapplemusic.com, but now I no longer do. I found a way to remove its access to your account, however. Go to App Store —> tap your profile picture —>under the account access heading, choose Apple Music—> from here you can remove an app’s access to your Apple Music and media library.
I would recommend doing this if you are concerned that a website is messing with your account, or if you are no longer using this website.
Edit: spelling and grammar