Off-side lineup qusetion

[Steve M]

Softball umpire here, after several adult beverages so forgive me if I phrase somethin wworng.
Other than the fact that its was not called, whay was Ftzgerald not flagged for being offsides - or lining up in the neutral zone - on his tocuhdowm catch
in the last 2 minutes of the superbowl.
I realize that I'm showing my ignorance here, but what are the requirements of the offense - in the pro game - for the line of scrimmage?

thanks for your clarifications,