Delayed 5th foul call

[abode]

A foul is the player's 5th foul but the scorers table misunderstood the player number from the referee and the error is not corrected until the first free throw has already been made.

Does the first free throw already made count or is it a "do-over" (so to speak).

The coach of the player with 5 fouls argues, “The first made free throw shouldn’t have counted. There’s an illegal player on the court. Whether it’s the fault of the scoring table, it’s a correctable mistake and the shot shouldn’t have counted.”