Crea APP for show website content

Development of an integrated system that allows the content currently available inside the website’s private user area to also be displayed inside a mobile application (Android and iOS).

All data is already stored and managed through the existing backend (PHP + MySQL) and users currently access their private area via browser, where they find materials and documents — mainly PDF files — organized into folders and sub-folders.
The purpose of this project is:
Create an API service
Develop a REST / JSON API layer to expose the existing backend data
Secure authentication with token based on the same login credentials used on the website

Endpoints for:
Login
Reading folder / sub-folder structure
Listing files
Retrieving direct PDF URLs
The API does not manage or create new content: it must only expose what is already uploaded via the website’s backend.
Mobile App development
Creation of mobile apps (native or cross-platform) for Android and iOS
User login with the same credentials used on the website
Display of folders → sub-folders → documents
Open PDF files directly inside the app
Real-time synchronisation with the website content (no duplication of data)
Simple and clean UI focused on document consumption