how this game end in a draw wtih chess 3 times repetition?
The positions after black ́s moves 47, 49, and 51 are exactly the same, hence draw.
Because it it third time repeated position, see positions after black's 47th, 49th and 51st move.
It might be helpful if the move list showed a hint which previous positions were the same when a game ends due to 3rd or 5th repetition.
