Usually, this is the beginning of everything, before you write any code. You make this for other people, you need to know what other people need and look for.
Talk to people, make interviews, do analysis of the results, see what's missing...
I searched for your product in Google Play but could not find it. I wanted to have a look and give honest opinion.
Three canceled immediately and one got to the paywall and canceled. You have a sample size of 4 users who engaged. That's not "optimize conversion" territory, that's "call them personally and ask what they expected vs what they saw" territory imo. A 15-minute call with each of them will teach you more than any onboarding A/B test from my experience.
If the three who canceled immediately say the same thing ("I thought this was going to do X and it doesn't") — well that's your answer and copy tweaks won't fix it. If they each say something different — the product isn't legibly positioned yet.
At 130 downloads with 2-9/day organic, you don't have a traffic problem. You have a "does this do something specific enough that people want" problem. Fixable, but only by talking to the people who bounced, not by guessing. You must established a channel of communication with your users.