If you are using old Windows, it will ask you to install .NET framework first.
Just click yes and download it first. Then run Book Keeper Windows setup.
Microsoft .NET is required for Book Keeper Windows. Microsoft .NET is preinstalled in latest version of Windows, if it is not installed, you can download it from Microsoft website.
Download link for .NET framework: https://dotnet.microsoft.com/en-us/download/dotnet-framework/net481
Kindly check this video and follow the steps.
https://youtu.be/WejR1f09YMM
Video tutorial for how to install Book Keeper Windows: https://www.youtube.com/watch?v=aCPjnGo7c9s