Can you get a small carrier, pen or a gate to keep the dog in an area where the cats can be close to the dog without being afraid of being chased/poked at by the dog?

When I moved into the house I am living in, ED the cat was kept in a closed room until he was used to the dog - Ed had was an indoor cat and he was visited by dogs when he would sit by the screen door.

He felt safe and got to know the dogs that way.

You can try that.