Data and People are Daz Studio Content folders. Poser files will be under Runtime, however Daz Studio also uses the Runtime folder for Textures, Legacy content, and Poser support files. Chances are with the Data, People, Runtime folders setup you are likely dealing with post Genesis era Daz Studio content (Genesis and Genesis 2 will work in Poser through DSON import/export and will often include poser companion files, Genesis 3 and 8 can be made to work via a complex workaround but whether DSON or a workaround they will not work as well in Poser as Poser native files)
So it sounds like you downloaded stuff for Daz Studio and not Poser native files. However good news is Daz Studio is free so if you don't already have it you can get it and use it and Poser both.