When we got Roxy she was excitable around the cats so we kept her leashed for the first few weeks until she learnt that she couldn't bother them too much.

Your cats need to build theior confidence around your new dog but won't be able to do this if they are being chased. Unfortunately your dog probably thinks this is great fun but your cats won't!

I don't think it's fair to expect the cats to live upstairs after all this was their home first so the new dog needs to know the rules. Once the cats are more confident they will probably 'tell off' the dog if she gets too close or bothers them too much but at the moment you need to be the one to teach the dog that the cats aren't there to be chased

Maybe do some clicker training with your dog & when she does leave the cts alone or sits nicely when they are near reward her for this rather than telling her off.

It will take time but I'm sure that you will get there