How to approve "Unapproved caller" whilst installing the software?
It seems it's some kind of temporary glitch, as it usually helps to restart the machine.

Other suggestions:


Reboot into Safe Mode, then Verify and repair drive


Reboot and hold the CMD+R keys
Select Disk Utility
Click on the image under my drive
Verify and repair drive

You may try to remove the cache files/folders located in /var/folders directory (not recommended) or move them into Trash.

Normally cache files should be cleared every few days by Launch Daemon (/System/Library/LaunchDaemons/com.apple.bsd.dirhelper.plist).

If the files can't be removed, reboot into Single Mode, run fsck, mount the root partition and run rm -vR -- /var/folders/*. Which is:


Start on single user mode: Hit the CMD+S keys at start-up
At the line, type (after root): fsck -fy and hit the Enter key.
Mount the root drive by: mount -uw /
Remove the cache files by: rm -Rf /var/folders/* (make sure you won't do any typo!).
Reboot by typing: reboot.