Content installation errors are frustrating and difficult to resolve without spending hours retracing your workflow.  DAZ3D zipped content differs from 3rd party zipped content in that they contain a primary folder entitled 'Content' in which all the subfolders are nested in the proper hierarchy found in the DS content Library.  For this reason, DS zips should be installed using DAZ Install Manager (DIM), a better alternative to manually copying folders/files to their proper locations.  DIM will automatically recognize and bypass the Content folder and copy the hierarchal files to where they belong.  This prevents the repeated instance of multiple 'Content' folders that can occur when blindly unzipping files to their destination.  

As to be expected, 3rd party content does not adhere to DAZ3D's zip conventions, so installation should be straightforward.  The problem arises when 3rd party content is unintentionally unzipped into an existing 'Content' folder, which shouldn't exist in the first place, and becomes undetectable by the software.  At this point, the damage is done.