Document Storage & Payment Mobile App

I'm looking for a mobile app that allows numerous users to securely save their documents. The app should also include payment functionality, enabling users to pay for premium storage options or services.

Key Requirements:
- only number data
- Payment Integration: The payment system will exclusively use Mobile Wallets. Freelancers with experience in integrating this payment system into apps are preferred.
- Cross-Platform Compatibility: The app must be developed for both iOS and Android platforms. Prior experience in cross-platform mobile app development is a significant advantage.

Ideal Skills:
- Mobile App Development (iOS and Android)
- Cross-Platform Development
- Mobile Wallets Integration
- Document Management Systems
- User Interface/User Experience Design

I look forward to receiving bids from experienced professionals who can deliver a high-quality product.