For the carrara content that is not stored in Poser library runtimes, I always "hand load" the content after installing first to a blank folder. I have a PC, so using windows, I go to the applications > DAZ> C6 folder and drag and drop the carrara content into the folders there. The new content has the names of the folder they go into.
When I do it like this, it always works. The content will be found in tabs like "scenes" and "objects". Some of the content will be found inside special functions. For instance: when you build a plant, you click on options and there are the new plants you bought!