Appeal deadline questions after an unemployment denial - any advice?

I got a denial letter last week saying I left my job voluntarily, but I was let go as an accountant. I have been trying to stay organised about it. 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 11 months ago, and it got easier once I kept a simple log of every call and form.