>>528696081
There's also a few hundred polys you can get from doing the tutorials here. Cooperation exercise especially.
Have you done Hollow Zero?
Shiyu Defense? Even if you can't complete it you can get a few hundred polys from just getting to level 3 or 4.
It's crazy you're struggling. ZZZ is one of the only hoyo games where it throws premium currency and pulls at you no matter what you do early game.