Hi @z_mge, if you log in to dropbox.com and hover over the folder and click the “…” (ellipsis) then you can click Share.
Click Share with Dropbox. Click Who can access that way you can see the members of each folder.
However, if the original account that the folders/files came from has been deleted, then our hands are tied.
Additionally, you mentioned that you no longer have access to either the email address linked to the account, or the account itself, which isn't ideal for us too.
Provided you could use the email in order for us to create a support ticket, then we should have more visibility to the edits, and files there.
But now, even if we switched to email communication, we would only see info from what you consider to be the new Dropbox account that you opened on your end.