See https://v17.angular.io/guide/setup-local for installing the needed tools like NPM.
Then install the dependencies with npm install and run the development web server with ng serve.
In angular most configurations like base URLs for API calls are done in environments under src/environment.
Runnin ng serve will use the mock environment from src/environment/environment.mock.ts.
All calls to external APIs are mocked. There is a development environment which can be configured under src/environment/environment.local.dev.ts to use a custom base url like http://localhost:8080/core but this wont work at the moment as CORS is not enabled server side. To use other environments, change defaultConfiguration under angular.json.
There is a prod image with all optimizations and the respective production environment under src/environment/environment.prod.ts and there is a debug image without optimizations.
This will provide clearer logs in case of runtime errors.