A very short summary is this: The fed congress sets the fed "election day" and anything that gets counted after that singular day isn't valid.
For questions concerning early "voting" and how that relates, it's all explained in
post #16 of that thread and then in "laymen's" terms,
post #23.
and anything that gets counted after that singular day isn't valid How many historical presidential elections, especially before the advent of computers, not to mention telephone and telegraph, do you think had all the votes counted by midnight on election day?