the Media Manager Structure is with own Categories and permissions. So the location it belongs to how the images are uploaded into Media Manager.
The attachment it self works by Drag and Drop in the PIM Desktop Client if you open the Document view with Items or Products. There is no direct way in Media Manager to link the Assets to items or Products.
Additional there are several ways to do a AutoAssignment or an Assignment by Referencewhich can be used.
Thanks, Ralph. Document view helped.
We were also able to upload and link images to the item via Web UI.