XeroTechnicalTest is a C# .NET Core 3.1 console application created using Visual Studio 2019. If you don't have Visual Studio, download the community edition from https://visualstudio.microsoft.com/vs/ Alternately, you can use VS Code and the .NET CLI by following the instructions at https://docs.microsoft.com/en-us/dotnet/core/tutorials/with-visual-studio-code Instructions for the test are listed in the comments at the top of InvoiceProject/Program.cs Good luck!