Yes you can download one page instead of the whole project in the Book Bolt Studio.
Once you are inside the studio and are working on a project, you may want to see or want to save one page, to look at or maybe print and see how it looks.
Click on the page you want to save on the left side.
Go to the menu at the top, click "Download", then click "Download Current Page CMYK (Printed Book).
The page will save to your default folder.
If you want to do more than one page, you just repeat the steps above.