Astrotalk-Style App System Design

I’m looking for a solid technical blueprint that will let my development team build a cross-platform (iOS and Android) astrology app with the polish and reliability of Astrotalk. The design has to cover... (Budget: ₹600 - ₹1500 INR, Jobs: Android, Chatbot, Content Management System (CMS), Database Design, Flutter, iPhone, Mobile App Development, Payment Gateway Integration, Security, User Interface / IA)