Ok so i've mainly been remebering the "It's me" hallucination from FNAF 1 & 2, but what if the "It's Me" was saying it's all in your head.
It's Me Hallucination - the reason it pops up as a hallucinations is to indicate all of the things happening around you is a hallucination, it's not real.
The Animatronics, All of them - You are hallucinating that they are coming to get you, You have created a situation of distress in your head from the articles you read.
Murders - Yes there were murders, but you heard about the articles and you got yourself spooked when taking the job, resulting in your mind playing tricks.
Marionette Music Box - You hallucinate it's a music box to distract a animatronic, but really it's just the phone. And the other night guard/phone guy checking up on you.
Phone Guy Dies - Just the phone lines cutting out, remeber it's a old building.
Death Minigames FNAF 2 - you remeber seeing old Freddy Fazbear Arcade machines and you have hallucinations about the machines and imagine strange and horrible senarios.
Freddy POV FNAF2 - You having a nightmare at your own house.
Posters and Articles changing - The articles change because you've read so many you've remeber each and everyone in great detail, you see them everywhere, the posters change mainly on your hallucinations if there isn't anything happening, no animatronics wandering hallucinations.
Phone Guy - You imagine him saying " The owners let them roam around at night, so their servos don't lock up" to creep yourself out and make you check cameras and waste power until you run out and it becomes so dark you hallucinate even more and worse, until you believe you have died.
6 Am - The only way to snap out of this state is when it turns 6 am, the reason that breaks the "spell", is because it's the only real sound you hear at all, also it tells you, you can leave, you're free.
This is one I just made up while finishing post - What if after you finish the 5th night or 7th (if you're a man) you go insane, even though you get fired and that relieves you. What if you go insane and commit the grizzly murders you read about and stuffed them in the suit. The hallucinations were warnings of what would happen (Unlikely).