Hi jweitzod,
there a different solutions that can probably help you.
When you share a folder, you can configure is in a way that it cannot be shared by others but only by the owner of the folder, which is you. This works with all kinds of Dropbox plans. Just go into the sharing setting, klick on the rack-wheel in top right. You can adjust that it only be shared by you, not by others. When using dropbox business, take into account that you cannot adjust those settings for folders inside Team Folders, depending on your Team Folder config. Consider sharing a folder which sits in your Private Folder instead.
As soon as you share a folder, even if your collegues only get rights to read it and not to write in it, it does not prevent copying files somewhere else.
Downloading an copying a file can be prevented when you share a link instead of a folder. You might consider sharing a link with your collegues, because this covers most of what you want to do.
Cheers,
Christian