Playstore point-gathering quest completed

I tried doing various things that seemed like they'd complete the quest after the first launch, and even after restarting multiple times, it wouldn't register because PlayGames wasn't linked. So, I played another tank game for about 15 minutes. The moment I relaunched this game, the PlayGames linking screen popped up. I linked it, did some battles, leveled up at the tavern, and did some random summons, and then it was complete. What a waste of time that first attempt was... If the linking screen doesn't show up when you launch, maybe try leaving it for a bit before launching? Also, for battles, there's an auto-battle option on the bottom left, so I didn't need to tap manually the whole time.