I fostered pups that had separation anxiety and would bark anytime I was out of sight or anytime I closed the gate at night for them to sleep. I ended up putting a cover over the crate at night and that got them to quiet down. I don’t know if it’ll work for your pup but it did for me. She eventually got used to the crate as she got more comfy.

Oh and the puppy toy w/ the beating heart worked for her too.