How can i find Root file of any Project?

I have just learned front end development and now i am trying to contribute to opensource, So i cloned a project https://github.com/chocolatey/chocolatey.org to make some code changes but when i opened a project on vs-code i just overwhelmed on seeing too many files and thousands of lines of code, Kindly tell me how can i find the root file of project, as we know if the app is build using reactjs we use npm start to run app and if app is build on nodejs we use node rootfile_name to run the app,, kindly guide me how can i find the root file so i can run and make chaning in the project. Thanks