How to play Ps4 Fortnite split screen?

I have a Ps4 with 2 controllers. I would now like to play with my son on the split screen.

Would be cool if someone can help me how to do it. Do not climb through the instructions on the net.

I have a Ps4 Network account.

I try to explain it to you clearly.

1 step: you start Fortnite with a controller and leave out the 2 roller.

2 step: when the game is started you can take the 2 controller and press the ps button then you have to log in with your 2 user.

3 steps return to the game and hold on the 2 controller for 3 seconds "X-KEY" then you should be in the "lobby" for two

So far you can only play duos, I would be happy to hear from you if my answer was helpful.