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See the article See your books and audiobooks on all your devices with Books on Mac - Apple Support

See books you’re currently reading, collections, bookmarks and more

1. In the Books app  on your Mac, choose Books > Settings, then click General.
2. Do any of the following:

• • Select Reading Now to see what books and audiobooks you’re reading across your Apple devices.
  • Select “Collections, bookmarks and highlights” to see your collections, bookmarks, highlights and recent book info across your Apple devices.

If it's a book you purchased through Kindle, make sure you have the kindle app installed.