Development of Ionic App for multiple platform distribution

General information for the app: Video content served from website.
Kind of development: New app from scratch
Description of requirements/features: We are looking for a Ionic developed app with distributions for iOS, Android, Windows, as well as a web-based app using a different domain to the main site. The app will show our video content in a similar style to our current video page on our website (see attached image)

The main requirements are:
1.User login using the website account credentials
2. Display videos served via the Wordpress Rest API - the videos are a custom post type, there are also custom post types for series and channels which determine the structure of the videos.
3. Limit content based on user - the Videos can be linked to our courses and can only be viewed by users on the course(s).
4. The videos are hosted by a service called Wistia, they provide an SDK for mobile development.
5. Customised code to extend the Wordpress Rest API to handle the above functionality.
Specific technologies required: Ionic, Rest API, Oauth, PHP, Javascript
Extra notes: