It sounds like you installed the preview instead of the free version for Ultimate. Uninstall the preview and follow these steps to fix it.
After uninstalling deskscapes, manually delete the "C:\ProgramData\Stardock\Deskscapes" directory and the "C:\Program Files\stardock\object desktop\deskscapes" directory if the uninstall process didn't delete them.
Download DeskScapes 1.02
Install DeskScapes 1.02
At this point it should work with all of the dreams in the gallery.