Cross Platform Quiz App

I need somebody to develop a Flutter or React Native quiz App, supported on iPhone and Android the app needs to support many quizzes divided by categories, there is a data model in Cassandra that needs to be followed, and all data including quiz title, images, answers, and questions need to be extracted from this database. The app needs to read data from a YAML file to get AdSense data and use it to show ads.
Once you send me a proposal I will not accept changes in value.