If an author is going to even mention depression in an SCP article, it's important to do it tactfully.
how do I go about conveying what it wants
Maybe it moves things around to form messages. Maybe it attempts to move objects around to imitate what would happen if someone was living in it. Maybe it exudes feelings of calm and aromatherapeutic scents.
and why it's doing this?
Give it a story to explain the reasoning behind the building's motives. What's the overarching narrative here? Did the house belong to someone with a depressed friend, did it belong to someone who worked as a therapist, did it house a host of depressed people? Does it get anything out of helping people?