Appeal deadline questions after an unemployment denial

My claim was denied after 4 weeks of waiting, and the letter says I have a short window to appeal. It has been weighing on me all week. My employer's version of events does not match mine, and I have emails that show it. Did you bring documents or only talk?

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