Download and update purchased books
If you previously deleted a book you purchased from the iBooks Store, the book is still in iCloud, and you can download it again when you’re connected to the Internet. If you have Family Sharing set up, you can also download your family’s books.
When updates are available for any of your books, you see the Downloads button 
in the top-right corner of your library or the iBooks Store.
Download a book
First, make sure that you’re signed in with the Apple ID you used to buy or download the book. To see the Apple ID you’re using, choose Store > View My Apple ID.
Note: Hidden books aren’t available for download.
In your library, click All Books, click Sort By (at the top right of your library), then choose Show iCloud Books.
If you see Hide iCloud Books, all the books you purchased are already being displayed.
Note: Purchased books appear in your library with an iCloud status icon
.Double-click a book that has an iCloud status icon to download and open it.
Download family members’ books
If you have Family Sharing set up, you can download your family members’ books. Make sure you’re signed in with the Apple ID you use for Family Sharing.
Click iBooks Store in the toolbar (or choose Store > Store Home), then click Purchased below Quick Links on the right.
Click your name next to Purchased, then choose another family member.
Click the iCloud status icon
for the book you want to add to your library.You may be asked to enter your account information.
Hidden books don’t appear and can’t be downloaded. For more information, see Share purchases with your family.
Download purchases automatically
You can have iBooks Store purchases you make on other devices automatically download to your Mac.
If you aren’t already, sign in to the iBooks Store on your Mac.
Choose iBooks > Preferences, then click Store.
Select “Download new purchases automatically.”
Update your books
Click the Downloads button
, then choose the books to update, or click Update All.
If you’re using iCloud for iBooks, books and PDFs that you imported on another device are automatically downloaded to your Mac as long as you have enough storage space.