I stopped playing while following the little girl.
-Complete lack of proofreading.
-Treating your players like fools with the box combination hint. You shouldn't have said "P.S. The code is your birthday" or whatever because the box was the only available puzzle and the memo was the only available clue. But you also messed that up. As Kylaila mentioned already nobody counts a person's year as their birthday. You did good enhancing the puzzle with some math (2-step puzzles are always better) but ruined it with the more-than-obvious clue.
-Cheap jumpscares are cheap. Something running by and making a sound is acceptable. Sounds on their own usually work better. But don't have something appear and then blink out of existence. If it vanishes because it has supernatual powers or whatever, use an animation. If it vanishes because it's super fast then have it run off at 2x speed (preferably in the direction the player will need to go, heightening the sense of caution and dread. Also, copy/paste the event with appropriate switches to multiple areas so you're not forcing the player into a 1-tile path between boxes or whatever just to trigger your jump scare. It gets pretty obvious that you have something evented on that one tile.
-So I could see just fine without a lantern but getting the lantern makes it harder to see? You should've included a short cutscene where the power goes out or demonic forces blanket the place in shadow or whatever.
-While following the girl, in the room with the body you can walk on the body and enter the wall. Then you're walking on walls.
-This is more of an intermediate game design technique so I won't dock you points for it but having them save point say it's an unused diary even when you already have a save made me chuckle.
-The story went out the window with a memo I found while following the girl.
Dude killed 99 people in one night? Did he have artillery!? Did he have a tank and they were all tied down? Really, if he just ran around stabbing people I'd be amazed if he got 6 before the others got away, somebody overpowered him, whatever. Luring them in one by one is time consuming and 99 is a hell of a lot of people. Also were you drunk when you wrote that memo? The typos in it are more like you're slurring your fingers across the keyboard.
Instead of typing all your text directly into the maker, write it all out in a word processor. Not only will this let you run spelling and grammar checks but you can also use guides to make sure none of your text goes out of bounds. Just copy/paste the lines in. This also has a motivational bonus since you can see a real-time progress meter for what percentage of your text has been put into the game correctly.
Another option if English isn't your native language is to ask somebody to proofread for you. The online community is great for that.