App Store Compliance Fix

I have a fully built iOS app (React Native / Expo) that is ready for the App Store but has been rejected multiple times due to specific guideline issues. I need an experienced iOS developer to help me get through the App Store review process and achieve final approval.
The app:

Built with Expo / React Native
Bundle ID: com.thehypertrophylab.app
Backend hosted on Replit (Reserved VM), domain: thehypertrophylab.com
Subscription monetization via RevenueCat ($14.99/month)
Codebase managed on GitHub

Current rejection reasons:

Guideline 3.1.2(c) — Free trial disclosure not clear enough in the purchase flow. Need the paywall updated to explicitly state trial length and post-trial charge amount before purchase is confirmed.
Guideline 2.1(b) — Purchase error occurring in Apple sandbox environment during review. Need sandbox purchase flow tested, debugged, and confirmed working end to end.

What I need:

Review the existing codebase and identify the root cause of the sandbox purchase error
Fix the paywall UI to display clear free trial terms (14-day free trial, then $14.99/month, cancel anytime) before purchase confirmation
Test the complete purchase flow in sandbox environment
Support through the resubmission process until the app is approved

Tech stack:

Expo / React Native (TypeScript)
RevenueCat for subscription management
EAS Build for iOS builds and submissions
GitHub for version control

Timeline:

As soon as possible — the app is otherwise complete and production-ready.
Budget:

Open to quotes. Please include your experience with App Store rejections and RevenueCat specifically.