Every time I try to enter a hard drive in Dolphin there is a pop up message
“Authentication is required to mount the device”
prompting to enter the root password.
but it didn’t help.
Are there any other security settings for HD mounting?
It is not quite clear to me what sort of device this is. Is it connected (and disconnected) during the up-time of the system? I ask because file systems that are on mass storage devices that are permanently connected (like revolving disks on PCI) are most often permanently mounted from boot to shutdown by having an entry for them in /etc/fstab.
You edited the wrong file. First, that one is for udisks, but KDE uses udisks2. Second, /usr/share/polkit-1/actions/ contains the package defaults and are overridden by the actual polkit configuration in /etc/polkit-1/rules.d/. Third, your change will be lost when installing updates.
Add the following line to /etc/polkit-default-privs.local instead: