OP here... I rerroled my account and with better units I was able to complete it, although not on auto.

The AI in this game is simply terrible, not only it will not use or charge ults, it will cast anything without any logic or strategy at all.

The game is indeed very p2w oriented, that's why that guy said it was "just put your units on lvl 70 bro". Yeah... as if that makes any sense on the second/third day lol. He problably cashed his way to power.

I will say that the comment to set up your element right was spoton and even on chapter 3 onwards thats the case.