Not all iBooks Author features are supported by Pages, so your imported book may look different from the original. If your book includes unsupported features such as certain widgets or a cover in a different orientation than the rest of the book, that content is saved in a separate folder for your reference.
Click the iBooks Author file once to select it, then choose File > Open With > Pages (from the File menu at the top of the screen).
You can also drag and drop the file onto the Pages icon in the Dock or Applications folder.
Do one of the following:
For a book with no unsupported content: Click OK in the dialog.
For a book with unsupported content: Click Continue in the dialog. Choose where you want to save the content folder for unsupported content, then click Save. (To see more locations, click the down arrow next to the Where pop-up menu).
To save the book as a Pages document, choose File > Save.
Choose where you want to save the document, then click Save.
You can make changes to your iBooks Author content in Pages before you this Apple Support article.