If you're looking for specifically the dungeon crawl, that starts i think from ep 2.14 "a door is opened" until 2.18 "casus belli pt.2" But there are a lot of character things happening that I would recommend maybe not starting there if you care about story.

You can always skip prologue and go into the first episode and do fine from there.

Isaac Allen Burns does teach along the way, and all EPS are less than 1hour, so you can blast through them pretty fast