The shapes come in a zip file that shows two folders when opened

1. Documentation
2. My Library

You can either extract the zip to the folder above "My Library" or
drag and drop the "My Library" folder to the existing one in the content folder.

If you use something other than "My Library" for your content,
then you will have to drag the folders underneath it to the respective folders.

To the best of my knowledge, these are the standard ways of installing content from Renderosity Marketplace.
I believe the merchants are required to package their products following this form.

I have configured DSON to look in DS for content so all the morphs appear in Genesis
with no additional effort on my part.

For other items, your must use a Poser Companion File supplied by the vendor or make your own

http://docs.daz3d.com/doku.php/public/software/dson_importer/poser/userguide/dson_content_conversion/tutorials/creating_dson_companion_files/start