Kotobee Author is required with a valid license, to create cloud ebooks. Once you have your ebook content ready, in order to create a cloud ebook, you will first go to the Export tab. For each of the formats (with the exception of Standard Files), you will find the option Convert to cloud ebook at the top of the page. 

The dropdown menu next to it provides you with three options:

Don't convert
This ebook will not be added as a cloud ebook, and will be publicly accessible (irreversibly).
Add as new book
A new cloud ebook will be created for this ebook. The ebook will gain all the features of the cloud ebook, such as controlled permissions, adding users, synchronized notes, encryption and DRM. By default, your cloud ebook will be “public”, giving permission to any user to access it.
Sync with Book
This will allow your ebook to be synchronized with an existing cloud ebook. The ebook will gain all the great features of the cloud ebook. All ebooks synchronized to this cloud ebook share the same space. If the cloud ebook is made public, all synchronized ebooks will be public. The same user list is shared between all, as well as their data (notes, highlights, and bookmarks).