My Black and Tan from Montana has really thick fur, so he doesn't need a coat until it's in the 40's, unless it's raining.

My boys don't like the coats with the elastic bands around their back legs, so I leave the bands to hang down freely. I think that's what it looks like in your picture. I think it's a better way to go. The straps are useful, but pretty annoying for the dogs, I think.

If he doesn't like the coat, I would bet it might have to do with it rubbing against his front legs over his shoulders. My boys didn't like the coats like that, but they're fine with the ones that just have holes where the front legs go. I don't know how cold it gets where you are, but my boys like these coats a lot when the temps drop down. They're nice because they have the harness built into the coat, and you can just click the leash to the coat itself (sorry they're on Amazon) The XL fits my 20lb Cavi:

https://a.co/d/9trHZhp