Implement a build server for dot net core project

Thanks, I was working with dot net core template.
Currently I am facing this error

MSBUILD : error MSB1003: Specify a project or solution file. The current working directory does not contain a project or solution file.

Dir in yml -

NOTE: Please edit this path so it matches the structure of your project!

SOURCE_CODE_PATH: ‘tutorialandtesting\TutorialAndTesting\TutorialAndTesting.sln’

I have tried all the possibilities - tried giving all possible paths with respect to both gitlab and local directory and with both \ & /.

Can you guide me with how to specify working directory?