the download button has disappeared from apple music . i can no longer add music to my library i cant only search and listen . do not share a link fix this problem sharing a link is not going to make my download button reappear

See if signing out and signing back in of Apple Music helps: Settings > [your name] > Media and Purchases.

You can also close the app and do a force restart:

Close an app on your iPhone or iPod touch – Apple Support (AU)

Force restart iPhone – Apple Support (AU)

I am also having this problem. When I search for an album in Apple Music I am able to see the "download" and "three dots" buttons in the upper right of the screen. When I search for the same album in my library, however, the "download" and "three dots" buttons are missing. This happened immediately after I updated my iPhone 11 Pro Max to iOS 15.4. It is a very annoying bug. Please fix it, Apple.

I am having the same issue