Multi-Platform Educational App Development

I need a skilled mobile app developer or team to design and build an educational delivery app for Android, iOS, and Web.

Key Features Required:
- User Authentication (Sign up / Login)
- Course Listing (Video, PDF, or interactive content)
- Lesson Tracking (Mark complete, resume where left off)
- Push Notifications
- Admin Panel (To upload, update, and manage content)
- Offline Access (Optional but preferred)
- Payment Integration (For paid courses)

The app should have a clean, modern user interface and be completed within a month. Ideal candidates should have experience in:

- Mobile app development (Android and iOS)
- Web app development
- UI/UX design
- Backend development for admin panels and content management
- Payment integration systems

Please provide examples of previous work and a timeline for project completion.