From a much earlier post by Web:

Most dock creators don't use the .dockzip extension...me being one of them. I personally don't use the .dockzip for several reasons. 1) is that they create extra unnecessary folders that you don't need taking up more space and 2) Because they don't keep them all in one folder.

If you find any .dockzip files you can rename the extension to .zip and then send all the enclosed folders to your backgrounds folder on ObjectDock and they will work.Your backgrounds folder should be in the Stardock folder for ObjectDock...C:Program Files (x86)\Stardock\ObectDock\backgrounds...if you just get in the  habit of sending all dock backgrounds to that folder you will have no problems and less clutter.