How or what needs fixing the allow this update to complete.
Error reads: A critical update is required for Mac, but an error was encountered while installing update. Your Mac cannot be used until this is done.
MacBook Pro
This is a hardware issue. Most likely the Logic Board will need to be replaced, but the Top Case/Touchbar Assembly is also a possibility. You will need to take the laptop to an Apple Store or an Apple Authorized Service Provider to be repaired.
In the mean time you can try booting into Safe Mode and making a system backup before being serviced.
I have this same issue, did you manage to resolve it?
Critical update block when updating OS
