Collaborative Drawing Markup App

I'm in need of an Android and Web compatible application that allows users to markup drawings and see live updates. The app should have different user permissions, specifically Read-only, Edit, and Admin.

Key Features:
- Multi-user and multi-device compatibility
- Real-time collaboration with in-app notifications, a chat feature, and a commenting system
- Different user permissions (Read-only, Edit, Admin)

Ideal Skills and Experience:
- Proficiency in Android and Web app development
- Previous experience in creating collaborative applications
- Understanding of user permission systems
- Ability to implement real-time communication features within an app.