Mistake

The mistake: lichess.org/study/RYVypfOR
Please correct it so that in this / other case (s) it is possible to enter line 8 !! Thanks. (The question mark means my question.) :): D

I'm not sure what you mean.
Black won the game.

Black won because white has the first move. If white gets there first and black can get to the 8th rank on the next move, it is a draw if the black king gets to the 8th rank. See lichess.org/variant/racingKings for more rules.