Took a lot of tries, but I finally got it! Helped by getting a succubus on turn 2 after building a tier 3 milkman.
One thing I didn't get the hang of was buildings. I thought they were supposed to provide coins or stat buffs each turn, but it didn't seem like they did? It would also be nice if it was clear if buffs like the Mega Milk are permanent or just for one battle. 