Supplemental update 10.13.3 macOS High Sierra on mid-2010 Macbook Pro

Hi,

I am trying to install the supplemental update for macOS High Sierra 10.13.3 on my admittedly old Macbook Pro mid-2010 (with original hard disk, which according to Disk Utility is still chugging along nicely). So far, I get stuck in the update process from the App Store, and I have no idea why. I have tried several of the other suggestions done in various groups here (clean install after starting up from recovery partition, then install with stand-alone updater downloaded from Apple; starting up in safe mode to see if something is wrong with my computer, then clean install from the recovery partition, then install the stand-alone updater), and I am at a loss. Any suggestion from those in the know would be highly appreciated.

Kind regards,

Bas