For internal HDD use exFat. For offline update from a thumb drive, use a thumb drive that is 32gb or less and formatted in fat32.
SU-42118-6 update fail. Get the correct offline update package from sony. There are two different kinds. One is JUST an update, the other is a reinstaller+updater for when you are installing a fresh new internal drive. The Process is the same but the files are very different.
If the internal drive is fresh/new/blank, you need the full reinstall package from sony.
In either case, do an offline update.
https://www.playstation.com/en-us/support/hardware/ps4/system-software/
Scroll down to which of the two is appropriate. Either the "Update system software using a pc or mac" section or "How to reinstall the PS4 console system software" section.
Sounds like maybe SU-42118-6 might be happening because the internal drive is blank in which case you need the reinstall ps4 console system software package.
An update file can't be applied to a blank internal drive, and full system software can not be installed via the internet. Good luck.