A file manager is necessary !?

[Me.B]

Building such module would not be so hard. I even took time to check that ajax explorer aka pydio works fine on a normal hosting:

https://pyd.io/

BUT my concern is always having such features executing within the panel context.
In my own setup I move off webmail/phpmyadmin to a custom subdomain for my customers, so I can maintain it & ensure it's locked down ( less privilege than execution into sentora sub domain).

Check monstaFTP that will use the ftp access to upload/ manage/edit files & works great.

M B