I didn't think this was the kind of thing that needed addressing, but given the number of fics that are failed for it on a consistent basis, and the fact that 75% of those fics come back with the problem completely unaddressed, it seems like we need to have a talk.
Paragraph separation.
It is not a complex concept. Maybe the idea of a 'paragraph' is alien to some people; if that's the case, I would urge you to educate yourself on the subject. There's a helpful article available Here – but, to summarize, a paragraph is an indentation/line break in a piece of writing that establishes: a piece of dialogue or new character speaking; a new thought or action separate from one prior; a change in time or location; a dramatic pause.
Or, you know. You can just put them wherever. Paragraphs exist to help assist reader absorption of your story, and to let them know when it's okay to make a mental skip in the flow of the action or narration. They also keep your story from being a completely unreadable wall of text. Consider the following two examples. First, without paragraphs:
"Hey Twilight!" Rainbow Dash yelled. She had a crazy hat on that was like a top hat as she flew real high up into the air and then came back down to Twilight's balcony. "Rainbow Dash?" said Twilight, surprised that Rainbow Dash was there. Rainbow Dash landed on the balcony with a 'poof' that made dust fly everywhere. "What's happening, egg-head?" she asked, and flipped her mane in a flippy fashion. She was so totally cool, Twilight could feel herself swooning just from the site of her cyan blue periwinkle deep-sea coat and prismatic multichromatic rainbow mane. "Wow, Rainbow Dash, you sure are an awesome pony," Twilight said. "Thanks Twilight," said Rainbow Dash. Her voice was totally cool, just like her. That's why Twilight was secretly in love with Rainbow Dash, even though she coudln't tell anypony. She thought about Rainbow Dash every day, even when she was brushing her teeth, because the colours in her toothpaste reminded her of Rainbow Dash. Twilight had thought about telling Rainbow Dash that she loved her, but she was afraid Rainbow Dash would tell her that was dumb, and that she would stop being Twilight's friend. She was afraid that even if Rainbow Dash didn't hate her, she would reject Twilight's confession, and the two of them would never have sweet lesbian makeouts ever. Rainbow Dash, meanwhile, didn't know any of this, nor did she think about it, because she was too busy being a totally super cool pony. But, if Twilight had told her, she would have totally said yes to lesbian makeouts. That's why the whole thing was so awkward.
Versus:
"Hey Twilight!" Rainbow Dash yelled. She had a crazy hat on that was like a top hat as she flew real high up into the air and then came back down to Twilight's balcony.
"Rainbow Dash?" said Twilight, surprised that Rainbow Dash was there.
Rainbow Dash landed on the balcony with a 'poof' that made dust fly everywhere.
"What's happening, egg-head?" she asked, and flipped her mane in a flippy fashion. She was so totally cool, Twilight could feel herself swooning just from the site of her cyan blue periwinkle deep-sea coat and prismatic multichromatic rainbow mane.
"Wow, Rainbow Dash, you sure are an awesome pony," Twilight said.
"Thanks Twilight," said Rainbow Dash. Her voice was totally cool, just like her.
That's why Twilight was secretly in love with Rainbow Dash, even though she coudln't tell anypony. She thought about Rainbow Dash every day, even when she was brushing her teeth, because the colours in her toothpaste reminded her of Rainbow Dash.
Twilight had thought about telling Rainbow Dash that she loved her, but she was afraid Rainbow Dash would tell her that was dumb, and that she would stop being Twilight's friend. She was afraid that even if Rainbow Dash didn't hate her, she would reject Twilight's confession, and the two of them would never have sweet lesbian makeouts ever.
Rainbow Dash, meanwhile, didn't know any of this, nor did she think about it, because she was too busy being a totally super cool pony. But, if Twilight had told her, she would have totally said yes to lesbian makeouts. That's why the whole thing was so awkward.
While both of those are reprehensible examples of proper storytelling, one of them is much kinder on the eyes, and easier to parse besides.
This is something I'm harping on because, perhaps in a completely foolish manner, I'd like to see the quality of stories on the site raised a bit. Requiring basic grammar was a big step in the way the approval process works, and this is just a slight honing of that; there is not a single body of examination of writing (including your high school English class, unless your teacher is really dumb) that will even look at something you've written if you don't separate your paragraphs in some fashion. Indents are the convention in standard fiction, but given that the site's GDoc import tends to ruin indenting, line breaks are something a lot of people use, which is totally fine. The key thing is:
Please.
For the love of all that is holy.
Make paragraphs
Separate them.
And don't complain if your story gets failed for having a giant wall of text with no new lines to speak of.
Cheers!