Nothing appears to suggest that that particular error is occurring. No information is provided by Windows at all as to why the update fails other than "Last failed install attempt on [date] - 0xc1900101.
Also, I am not running Corsair Link anymore, I'm running iCUE. As I understand it, iCUE provides same functionality as Corsair Link - meaning if I have iCUE I don't need Corsair Link - is that right? Changing to iCUE seems to make no difference to the failure mode.
However - I do have CPU-z (v1.93.0 dated August 2020) installed. So, I removed that, unplugged USB devices other than mouse and keyboard, repeated the install of Win10 2004 and it still fails. All failures occur at about the same point - after the 2nd restart (the first restart is manually initiated, then the second is automatic) about as progress reaches 28%. At failure, the screen goes black, and the machine restarts, and large text reports that it's undoing changes etc.