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 a hotel front-desk agent. This is my first time dealing with any of this. The letter lists a deadline and a hearing process, but it is hard to follow. Did you bring documents or only talk?

Legal aid offices and some workforce centres help with unemployment hearings at no cost. A call is worth it.