How to fix greyed-out music not syncing on iPhone and iPad without a computer?

music on sync but not syncing I don't have a computer I only have a Iphone and Ipad in settings in the music App I have Sync across devices but when I open my music library some music is greyed out and if I try to play it I get the message turn in sync music ? Which is switched on ?

[Re-Titled by Moderator]

Original Title: Sync Apple music