内容来源：https://www.engadget.com/2307469/how-to-sync-apple-music-across-devices/

内容总结：

苹果音乐跨设备同步设置简便易行。作为当前主流音乐流媒体平台之一，苹果音乐虽与苹果生态深度绑定，但并非苹果设备专属，用户可在安卓手机、Windows电脑甚至智能电视上登录Apple账户收听音乐。然而，在新设备上登录后，用户可能会发现音乐库未同步、歌曲缺失。对此，只需调整苹果音乐中的一项设置即可实现跨设备同步，无需逐台设备手动管理。

同步失败的主要原因通常是各设备登录了不同的账户。用户可在苹果音乐应用首页点击头像查看当前登录的邮箱地址，若与主账户不一致，应退出后重新使用主Apple账户登录。随后需确保各设备已开启“同步资料库”功能：在iPhone或iPad上，进入“设置”找到“App”列表中的“音乐”应用并启用该功能；在Mac上，打开音乐应用，点击屏幕顶部的“音乐”菜单进入“设置”，在“通用”选项卡中确认已启用“同步资料库”并保存；Windows端操作基本一致，但需点击三点按钮进入设置；安卓手机则该选项默认开启，无需额外操作。首次同步可能需要一定时间，音乐库较大时尤为明显，启用同步后若歌曲未立即显示，保持音乐应用打开并等待数分钟即可。

若同步仍未生效，Mac用户可通过“文件”菜单进入“资料库”选择“更新云端资料库”强制同步，Windows端也可在侧边栏找到该选项，但iOS和安卓应用不支持此操作。同时，应确保移动设备连接Wi-Fi且未处于低电量模式，以免影响同步。若上述方法均无效，可尝试关闭后重新开启“同步资料库”，或退出Apple账户后重新登录。对于未订阅苹果音乐、仅在Mac或PC上拥有离线资料库的用户，唯一方式是通过Apple iTunes或Apple Devices手动将音乐文件夹传输至另一台电脑。此外，用户还可在设置中探索其他选项，例如调整音质以启用无损音频。

中文翻译：

在设备间同步Apple Music比你想象的更简单
在多台设备上使用Apple Music？让它们保持同步轻而易举。
Apple Music是目前最好的音乐流媒体平台之一，尤其对苹果设备用户而言。不过，尽管它与这家科技巨头紧密关联，Apple Music并非苹果设备专属，而是可在多个平台上使用。例如，你可以用Apple账户登录，在安卓手机、Windows电脑甚至智能电视上收听你喜欢的歌曲。
不过，在新设备上登录后，你可能会发现音乐资料库没有同步，歌曲也不在那里。如果你遇到过这种情况，不用担心。只需更改Apple Music中的一项设置，就能让它在你所有设备间同步音乐，确保你不必在每台设备上手动管理资料库。
如何开启Apple Music的同步资料库
Apple Music可能不会在设备间同步资料库的主要原因，是你在每台设备上使用了不同的账户，所以请先检查这一点。如果不确定自己用的是哪个账户，打开Apple Music应用，在“首页”标签页点击你的头像。如果未同步设备上的电子邮件地址不一致，说明你登录的是其他账户。请退出登录，然后使用你的主Apple账户重新登录。
接下来，确保你的设备上已启用同步资料库。在iPhone或iPad上，打开“设置”，找到“App”。然后，在列表中找到“音乐”应用并启用同步资料库。在Mac上，打开“音乐”应用，点击屏幕顶部的“音乐”菜单，然后进入“设置”。现在，在“通用”标签页下，确保同步资料库已启用，并点击“好”保存设置。在Windows上的操作基本相同，但你需要点击三点按钮才能找到“设置”。如果你使用的是安卓手机，此选项默认启用，无需更改任何设置。
无论哪个平台，首次同步都可能需要一段时间，尤其是当你的音乐资料库很大时。如果在启用同步后没有立即看到你的歌曲，请保持“音乐”应用打开，等待几分钟。
Apple Music无法同步时怎么办
在Mac应用中，点击“文件”菜单，然后进入“资料库”并选择“更新云端资料库”——这将强制应用同步并检查你的个人资料库中的更新。此选项在Windows应用中也可用，可在侧边栏中找到。遗憾的是，安卓和iOS应用没有该选项。
另外，请确保你的移动设备已连接Wi-Fi且未处于低电量模式，因为这可能会阻止它们同步你的音乐资料库。如果其他方法都不奏效，最好的选择是返回“设置”，关闭同步资料库，然后重新开启。你也可以尝试退出Apple账户后重新登录。如果你没有订阅Apple Music，并且在Mac或PC上有离线资料库，同步资料库的唯一方法是通过Apple iTunes或Apple Devices手动将“音乐”文件夹传输到另一台电脑。
同步行为并不是你在Apple Music中唯一可能想要更改的设置。趁此机会，不妨探索其他一些开关选项，比如更改音质选项以启用无损音频。

英文来源：

Syncing Apple Music across your devices is easier than you think
Using Apple Music on multiple devices? Keeping them in sync is a breeze.
Apple Music is one of the best music streaming platforms right now, especially for Apple device owners. But despite its association with the tech giant, Apple Music is not exclusive to Apple devices and is available on multiple platforms. You can, for example, sign in with your Apple Account and listen to your favorite songs on an Android phone, Windows PC or even smart TVs.
After signing in on a new device, though, you may notice that your music library isn't synced and your songs aren't there. If this has happened to you, don't worry. Changing a single setting in Apple Music will prompt it to sync your music across all your devices, ensuring you don't have to manage your library manually on each one.
How to turn on Sync Library on Apple Music
The main reason Apple Music might not sync your library across devices is that you're using different accounts on each device, so check that first. If you're not sure which account you're using, open the Apple Music app and tap your profile picture on the Home tab. If the email address on the unsynced device doesn't match, you're signed in on a different account. Sign out, then log in using your primary Apple Account.
Now make sure Sync Library is enabled on your devices. On your iPhone or iPad, open Settings and look for Apps. Then, find the Music app in the list and enable Sync Library. On a Mac, open the Music app and click the "Music" menu at the top of the screen, then go to Settings. Now, under the General tab, make sure Sync Library is enabled and click OK to save your settings. The process is pretty much the same in Windows, but you need to click the three-dot button instead to find Settings. If you have an Android phone, this option is enabled by default, and you don't need to change anything.
No matter the platform, the first sync might take a while, especially if you have a large music library. If you don't see your songs right away after enabling syncing, leave the Music app open and wait a few minutes.
What to do when Apple Music won't sync
In the Mac app, click the File menu, then go to Library and select Update Cloud Library — this will force the app to sync and check for updates in your personal library. This option is also available in the Windows app and can be found in the sidebar. Unfortunately, the Android and iOS apps don't have that option.
Also, make sure your mobile devices are connected to Wi-Fi and not in Low Power Mode, as this may prevent them from syncing your music library. If nothing else has worked, your best option is to go back to Settings, turn off Sync Library and then turn it back on. You can also try signing out of your Apple Account and logging back in. If you don't subscribe to Apple Music and have an offline library on your Mac or PC, the only way to sync your library is to manually transfer the Music folder to another computer via Apple iTunes or Apple Devices.
Syncing behavior isn't the only setting you might want to change in Apple Music. While you're there, it's worth exploring some other toggles, like changing the audio quality options to enable lossless audio.