Import books, audiobooks, or PDFs in Books on Mac
If you have books or audiobooks that you didn’t get from the Book Store or Audiobook Store, or PDFs that you want to open in Books, you can import them into Books.
In the Books app on your Mac, choose File > Add to Library.
In the Open dialog, select the books, audiobooks, or PDFs you want to import, then click Add.
If you have imported books, audiobooks, and PDFs on your other devices, you can use iCloud for Books to see them on your Mac.