Unable to install macOS 10.13.6 on mid 2012 macBookPro. Error: Disk does not meet requirements

I am trying to install macOS High Sierra 10.13.6 on macBookPro mid-2012 , macOS version 10.13.

I downloaded "macOSUpd10.13.6.dmg" for THIS site. Now, when I am trying to install it on my mac, it shows the error :

macOS High Sierra 10.13.6 update cannot be installed on this disk. The volume does not meet the requirements.

See the screenshot

I am not sure if this is the right way to update to 10.13.6 or may be the macBook mid-2012 does not support it anymore.

If anyone has experienced this error, please help me here.

Solution 1:

Unless you are already on 10.13.5 then you cannot update using the regular delta updater, you must use the combo updater, which will work for anything from 10.13.0 up to 10.13.5

Link is here Download macOS High Sierra 10.13.6 Combo Update

After [many] comments:-
If this doesn't work for you... then assume your own situation is not similar, not that the answer is wrong.