when i bring my fosters in my house, my cats will usually be in their room.
they have a room of their own, where no dogs are allowed (i highly recommend giving the cats a room or two of their own, where they can eat, sleep and poop in comfort away from the dog).
the dog doesn't have to be in the crate all the time, you can take him out, but he gets no freedom, so he's leashed to you. when you're done letting him stretch and follow you around, crate him again (give him a treat when he goes in his crate, remember to always keep the crate a positive place for him).
he'll sleep, he'll observe how the house is run, who comes and goes, what animals do etc..
this is an adjustment period for you and for him.
he doesn't know you. he doesn't trust you yet.
you have to work to gain his trust, and vice versa.
it by far easier training him the ways of the house early on, and that the cats are part of your pack, and not prey.