Why i can't launch fortnite on the OS 10.13.3 uptade on the macbook pro?

Every time I try to launch fortnite on the epic game’s launcher, it says I need the Os 10.12.6 uptade and really wonders me since i want to play fortnite badly and also I uptaded it to OS 10.13.3 mac uptade before i tried to launch the game.

i have the same problem can anybody answer ?