I did a quick look through the Scribd document and I didn't see a reference to "registered voters".
Where did you see that? It is very big news if true since Likely Voter polling is going to look even better for Trump and will be closer to the actual vote.
Even “likely voter” polls don’t tell the whole story since Donald Trump is bringing millions of new people to the voting booth, many for the first time.
A couple of articles I looked at said they were registered voters.