In most samples DHTMLX Widgets are loaded through NPM that provides limited (GPL) version of components. For production you should use the PRO version.
There are also samples where DHTMLX Widgets are loaded from CDN. cdn.dhtmlx.com serves limited (GPL) version of components. For production use your own CDN / file server.
Run ng serve for a dev server. Navigate to http://localhost:4200/. The app will automatically reload if you change any of the source files.