bookings.json and hotels.json have to be placed inside Data folder before building the project or after building the project those files can be updated.
Application is also configured using config.json file which contains paths to bookings and hotels data files (json). config.json is loaded only once when config is used for the first time.
Navigate to root project folder Guestline.Roomradar (This folder contains this readme.md) and run command dotnet run --project ./src.