my apple music won't play on my Mac book.it only works on my iPhone?

If you have an Apple Music subscription, then you have to use the same Apple ID on all the devices. For Macs, that means logging in to your account in the iTunes application (menu Account).

Apple Music features and the iCloud Music Library may have been turned off in iTunes Preferences. You can toggle the switches to ‘on’ to have those features in iTunes.

Please specify your MacBook model by year/season and chip and macOS version, as shown in menu﹥About This Mac.