Error 404 select from server path

Hello,
I am trying to resolve this topic from a while (I wrote more than a year ago and I didn’t get the solution!) and I need help, really.

The “Add from a server” function, in “add new download” doesn’t work. It gives me Error 404 page.
The Asset manager works perfectly instead, so I presume the path is correct.
The plugin is updated to the last version, but it is from some release ago that broke up (before, same server path, worked perfectly).

Can someone help me, maybe it’s a stupid thing…
The website, password protected, is on a Aruba shared server service.
/home/-myarubaserver-/-websitedir-/wp-content/uploads/download-manager-files
Tried with the final / and without… same bad result.

I’m looking forward for someone kind enough to help. Thanks in advance.
Eva