If you are using a recent version of DAZ Studio you are probably still in Category view, which shows only files that have been added to the database. In DS, go to the Content palette and click the triangle button at the extreme top-right (next to the pushpin icon) and from the Option menu either pick one of the View fodlers as options at the top or do a search for new files to add them to the Unassigned category, drom whence you can move them to your desired category for M3. As renmrk notes, you need to point the installer to the Content folder in the folder you installed Studio to (you can put things elesewhere, but then you have to tell DS which other folders it needs to look in)**.
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