Can't find a person in The following (Dying Light)

I played for a long time, I don't remember exactly. Either you need to look for a door inside, or go further along the plot and after the task with the power plant there will be an additional one. a mission where children ask for help and already in this mission they will "open" the door

Xzematik
Follow the storyline, there in one of the missions you can open the closed gate

ImTheGREED
I didn't think about it, thank you very much, I will take into account

Angry fairies
Thank you so much for the video too