Multi-Platform Course App Development

I'm looking for an experienced developer to create a multi-platform (Android, iOS, and web) app similar to the Shikho app. The app will feature 10-minute long video courses with sub-courses, and will have the following functionalities:

Essential Features:
- Video Playback: Users can watch course videos.
- Course Progress Tracking: Users can track their progress.
- User Authentication: Secure login for users.

Additional Features:
- In-app Purchases: Users can buy additional courses or content.
- Push Notifications: Alerts for new courses, updates, etc.
- Offline Access: Download courses for offline viewing.

Access Control:
- Subscription-Based Access: Users need a subscription to access content.

The app will be managed by one admin only, and will allow only one device login per user.

Ideal Skills and Experience:
- Expertise in mobile and web app development
- Experience with video content integration
- Strong understanding of subscription-based models
- Familiarity with push notifications and offline access functionality
- Solid background in user authentication and progress tracking systems

Please provide examples of similar work done. Looking forward to your bids!