Narration and Structure -
Overall, this article reads very dry. It's an unfortunate combination of clinical and straightforward. That first part isn't entirely your fault, because this site insists on maintaining the SCP Foundation's adherence to clinical tone for reasons I don't really understand. That second part is a different story, though. If you're going to adopt a dry, clinical, technical professional tone for your writing, the content and subject of that writing needs to be something that causes raised eyebrows and scratched heads. You need to juxtapose that tone with something really out-there and wild and maybe even difficult to parse. Otherwise you're writing about pots and doorways with all the passion and intrigue of furniture assembly instructions.
You do lead into some descriptions of fantastical things further down, these "Shadows", but you don't use the clinicality of your diction to even have any fun getting into detail about their behavior, makeup, properties, anything. You just kind of drop that bomb and move on. You're not really teasing me with anything with this, you're not giving my brain anything interesting to chew on. It's just Shadows with a capital S, for some reason. Kind of video-gamey, not entirely original, to be frank.
Your Entrances and Exits section is… this is kind of a problem I have with this site's article format in general, but what does this section do, precisely? What information is being conveyed here? These doors lead to other parts of the backrooms. Mhm, that much is pretty obvious. But how does this section enhance the article? It's just a list of other articles. I'm not left with any greater sense of any of this piece's substance, you're not using it to convey any amplifying information about this location or anything in it. It's just some numbers that I can click on to read more backrooms articles. If the rooms being referred to here are actually somehow thematically relevant or important to the concepts in the article, I wouldn't know. I haven't read most of them. So what am I intended to gain from this section? It's just kind of borderline contentless, and an opportunity where you could have done something inventive, that tells me about how weird or uncanny your space is.
Overall, this article's word-by-word assembly is… I would say barely passable. There are "as if"s, "seems to be"s, and other wimp-outs or redundancies sprinkled throughout, making the article bloated and sluggish despite not actually being very long at all. It's mostly grammatically sound and largely intelligible, it's just… not very lively.
Characterization -
So, your demon… fellow. The entity's personality is threadbare - the most I can call it is "theoretically villainous" and… I dunno, polite? I guess? It doesn't spend any time explaining anything about itself and it doesn't say anything thought-provoking or meaningful, it just kind of recites some handwavey evil lines I've heard other cartoon villains say hundreds of times at this point. I'm not interested by anything this character says, which means I'm not going to be scared or sympathetic or any other emotion. I just want to change the channel.
Rita is slightly better, in that she shows some indignation throughout the process, but I'm confused about her role. I'm not really told why she's here, what she's supposed to learn, or what specifically her job is. She behaves sort of unprofessionally and flippantly throughout the interview, so, I'm left to assume she's kind of new? Or at least wasn't adequately prepared to be doing this kind of thing? Outside of that, as with her antagonist, you haven't given me a lot. Most of her statements are very rote and mechanical - she doesn't even react all that much when the creature causes her text font to change for… reasons I'm not really sure of. I can't help but feel that you left a lot of meat on the table, with both of these characters.
Concept -
So, let's look at everything you're actually describing here. With all the information given to us in the article, this is small stone pavilion kind of space with some doorways. Most of these doorways go to other places, and the main door leads to a kind of prison housing a cyclopean demon man thing. Time passes faster in the prison than it does outside. The entity contained within the cell is… nefarious. In a sort of vague, ill-defined way. It's been down there for a very long time, some other entities used to worship it, but they betrayed it and left it to rot here. It is upset about that. This last bit is kind of confusing, actually, I think it possesses Rita and uses her to escape? Or… it touched her and… made her all brain-poopy? I honestly have no idea, you didn't leave me with much to work with.
And… that's it. You didn't really use the interview as an opportunity to show the reader an interesting bit of lore or expand on why any of this exists. There isn't really anything original on display here. And that doesn't necessarily need to be a fatal problem, if you at least paint an entertaining picture with tropey paints, which you seem to have forgotten to do. It sort of reads like you were just trying to fill as much space as possible without actually telling an impactful story, or at least alluding to one. Where did the demon creature come from? Who built this place? Why did the race of… things betray the prisoner? What exactly happened to Rita? Is she going to be alright? Did the creature gain something from this interaction, or did it just… kind of fuck with her? Why does it say it will see her again in two years? I don't need concrete answers to these questions - just handing them to me would take the fun out of it. But you haven't even hinted at any of them. You haven't given me enough to chew on that I can even possibly come up with my own answers - or if you have, you've done it in such a vague way that there really isn't a difference.
This article is a skeleton, but it's not even the kind that wears a funny top hat or dances around. It's just kind of lying there. Next time you're putting something together, think about what information you're giving your reader. Think about what all they're going to be left with by the time they get to the bottom of the page, and whether it's going to be entertaining, or at least memorable.