Steam multiplayer join black screen

I feel like crying i cant fix this! So I was following this tutorial: Blueprint Multiplayer: Project Overview | 01 | v4.11 Tutorial Series | Unreal Engine - YouTube

It was all going good, i created a session from my pc and tried to join from laptop but i got a black screen on laptop when i pressed accept (to join).
I am attaching my project files, please take a look, I am literally trying to fix this for days now!