User file manager

Hi
I’m searching for a plugin that, from a page, after user identification with userid and password with captcha, let user manages files in one directory that the administrator selects for that userid (maybe with graphic directory list … as a “file manager”).
In alternative could fit one that do the same thing from wp-admin login (where captcha is already working) but it shoud make that the user can only manges files and nothing more.
Does a plugin exist that can do that?

Thanks