Update:
I tried to build Unreal from source and had file permission errors.
I saw on a forum that utils or anti virus may be holding on.
That sounded like a clue and so I tried disabling the anti-virus for the Launcher install and Success!
It took around 3 hours to move from 82 to 83% but then progressed from there.
An option to try for others if they get stuck after it completes the downloading portion.