Social Network for Apartment buildings

I need an app developed using Flutter so that we can have an Android and IOS app. The app will allow a user to select a country and then select an apartment block that they live in. They will then be part of the social network for that apartment block and they will be able to get notifications from admin, be able to post classified adverts, be able to post property adverts and be able to see a business directory. There must be an inbuilt messaging platform in the app so users can message each other.