How to teach kitten to cover her poop and pee in the litterbox ?

So I adopted a kitten from a lady on Facebook, and I believe she lied about everything. She had said the kitten was 6 or 7 weeks old when I got her, then said her birthday was 5 weeks ago. Immediately I knew something was wrong when she hissed at me and had her back arched when I got home. Then came the litter box.

So I have 4 cats (3Y Female, 2Y female, and 8W female) they all get along and play. I have 5 litter boxes. The new kitten (Lily) pooped outside the litter box for the first 2 days. She would poop directly next to the entrance next to my scoop. She would only pee when I dumped her intro the box, but she wouldn’t cover it. Now when she poop, she’ll go Into the box, but she covers it completely wrong. She moves the litter across from where she went poop or pee and won’t cover the actual landmine spot. She’s also started a problems of trying to cover the walls of the litter box. She’ll scrape her claws on the acrylic walls for a solid 2 minutes and won’t touch the actual litter.

I decided to try and dump my 8W kitten into the box after lily is done. She’ll cover it and I’m hoping lily will learn from her. Lily acts as if she’s never covered her poop or pee before. All the kittens I’ve fostered or adopted knew that much, even when I saved my 8W when she was 4 weeks old.

Am I doing this right? Or is there an underlying issue.