It takes time for them to be friendlier with each other. The kitten should have her own room so they can sniff under the door. Put her food and water in there, and a small litterbox. You can make a temporary litter box out of a cut-down cardboard box.

Also, help them get used to each other's scent. You can wear an old t shirt and cuddle the older cat a lot, and then put that shirt in with the kitten.

Wear a different shirt to cuddle the kitten a lot, then put that shirt where your older cat will smell it a lot, like a favourite sleeping place.

Try introducing them several days after you separate the kitten from your older cat. Even when they start getting along, there will be some hissing as the older cat lets the little one know who's boss!

Has your kitten been to the vet for a checkup yet?

I am sure they will get along, given a little time.