There are no more DAZ installers, that is a thing from the past.  For V4, you do not need the DSON Importer; that is strictly for Genesis and Genesis 2 as mentioned from a previous post.  The initialization is a must as also described.

When creating a new external runtime folder follow the instructions Mahakali suggested. Except don't attempt to create the subfolders within the runtime folder.  Allow Poser to do that for you.  Simply add the runtime to Poser and the Library will automatically create the necessary subfolders.  You can even create a runtime through the add runtime feature in Poser.  When the navigation window opens, click add folder button on the lower left, create a category folder, click the button again, then add the runtime folder.