Math Course Study App Development

I need a complete mobile application that lets students buy and study academic-subject courses on both iOS and Android. After a single, one-time purchase, a learner should gain full access to every lesson, interactive quiz, video lecture and discussion forum attached to that course... (Budget: ₹600 - ₹1500 INR, Jobs: Android, Android App Development, App Developer, App Development, Backend Development, Flutter, iOS Development, iPhone, Mobile App Development, Payment Gateway Integration)