Crate training newly rescued dog

Hi!! I adopted a 1 year old terrier about a month ago. He’s pretty anxious and very attached to us follows us around, sleeps by our heads).

We would love to crate train his so he’s comfortable if he ever needs to stay overnight somewhere plus we want our cat to have freedom at night to cuddle with us and roam the house. They get along okay, but cat is not very fond of dog.

When we first brought our dog home, we focused on bonding with him and therefore let him sleep with us as he pleased. We’ve been feeding him in the crate, and he will sometimes go to sleep in the crate (next to my desk) during the day.

He is very nervous to go I. The crate still, keeps his hind legs out when we throw treats inside and certainly doesn’t feel comfortable when it’s closed.

Is there any hope for crate training him to sleep in during the night or when we’re away from the house?

Advice appreciated!!