Dang there is a lot of hate for this game here, like it's definitely not the best game ever but it is one of the most compelling mobile experiences out there, with a decent story that has some great moments, and it can absolutely be played completely for free without missing out on much. The only thing spending money is good for is specific characters and weapons, none of which are required, and you can absolutely save up from playing for free and get almost any of those characters/weapons without spending a dime.
It's not for everyone but I feel like this game gets a lot of hate simply for the Chinese origin, cartoony style, and microtransactions without any actual knowledge of what it's like to play it.