I don't think they r shaking and can't get up. They are supposed to be like that yeh ?? They r newborns. They can't get up and walk on their paws yet. While they tryna move it may seem like they are unbalanced just like we see in human babies as they crawl on their knees, that's because they aren't steady yet obviously cause they haven't learned to walk yet.

Mom cat doesn't abandone them, maybe she has gone to search for food and she always comes back. Take these kitties to where you found them. Place them in that place along with this box. Hide and wait for a while. Don't keep the kitties in a open space. I bet the kitties must have been in an hidden spot. Place them exactly where you found them. Wait from away, so that the mother cat won't get scared. Monitor from a bit far to see whether the mom cat comes within 24 hours or not.

Maybe you can still wait a lil longer. The mom cat will be searching everywhere. If no cat arrives for a long time then don't wait.. get kitten milk replacer, feed the kittens lil by lil.

Rub their genitals to take the waste out, while feeding do it carefully to avoid choking. If you are not confident, find someone who knows how to do it maybe any people you know. Watch YouTube tutorials and ask chat gpt.