server security lockdown is confounding merging images with metadata

Server security is preventing me from using features to upload and transfer images from the Dropbox plugin. When I deactivate Dropbox, I can only browse to my local workstation in File selection from an Item ... even though there are images in the Archive. I find that I can batch add metadata but cannot attach and upload files in the csv using filename or a url + filename.
Is there another way to get the image attached to the metadata record?

If you can attach files to items individually, I would have expected the CSV import to work.

Do you know what, exactly, the security settings are that prevent you from using Dropbox?