Github peachpie-wordpress gives error connecting to database

Hi, I installed the Peachpied project from nuget into an existing visual studio web app project. After following the readme, I ran the program and I got the error “Error establishing a database connection“.
When I google about this error, one of the things I see is that i need to check the wp-config.php. But there IS no wp-config.php in this demo project?
thx for any suggestions or advice.