Simple GPT-Powered Web App Development

I need a simple browser-based web app to host my ChatGPT-based Lean Work Instruction Assistant, designed to help users write standard operating procedures and work instructions. The app should have the following features:

User Functionality:
- Web form for task input
- Simple, clear GPT output
- One-time payment via Stripe

User Management:
- User account/login (email/password)
- Admin access for user management, resets, and activity monitoring
- Rate limits or credits per user

Notifications:
- Email notifications for user activities

Admin Requirements:
I need an easy-to-manage admin interface after launch.

Preferred Tech Stack: Node.js, Replit, Bubble, or any lightweight alternative is welcome.

Timeline: 5-7 days

Ideal Skills:
- Experience with OpenAI API
- Strong understanding of Stripe integration
- Web development with Node.js or similar technologies
- Familiarity with user authentication and admin panel creation
- Clean, mobile-friendly UI design

I’m not a developer, so the final product must be user-friendly for me to manage once live.