When you get the error above (see screenshot), it means that no connection could be made with the SQL server or no valid SQL Server is found on the machine.
Solution:
For the program to run, you must have Microsoft SQL Server LocalDB installed on your PC.
You can install this using the included installer in the .zip folder, or you can find it in the README.md page/file from this repo.
This error message from the installer of SQL LocalDB means that you probably don't have Visual C++ Redistributable packages installed.
Solution:
You can find and download the packages here!
More is coming...