Create a Football Referee App using App. Inventor

I need to create an Android app for football referees to use. This app must be created using App Inventor. Functions of the app includes: - Stopwatch - Insert teamsheet (connect to TinyWebDB and can choose team and players instead of inputting manually) - Make substitution of player (record which player is out and which replaced player is in) - Store and accumulate scores for each match - Show records of winning team in each match and seasonally - Whistles (once, and twice in a row) - Show Red/ Yellow card - Store data to TinyDB - Retrieve data from TinyWebDB Since we are undergraduates, we don't have monthly income. Hopefully someone who want to practice or is familiar with App Inventor could give us a hand and charge us not more than 1000. Thank you!