Appeal deadline questions after an unemployment denial - first time posting

I got a denial letter last week saying I left my job voluntarily, but I was let go as a customer-service rep. The letter lists a deadline and a hearing process, but it is hard to follow. Did you bring documents or only talk?

Thanks for writing this out. I went through something close to it 13 months ago, and it settled down once I kept a simple log of every call and form.