Is there a minimum track length?

If an audio track is less than 60 seconds long, music services may consider it to be a "snippet", which is defined in the Apple Music Style Guide as "a portion of a longer piece of audio purposely edited into smaller segments".

Including snippets can result in your release being removed from music services, so we recommend that you keep track lengths above 60 seconds.

One possible exception are intros, outros and interludes on multi-track releases.  If your track falls into this category, we recommend adding "(Intro)", "(Outro)" or "(Interlude)" to the end of the track title, to avoid any confusion.