Just like the instructions here Publishing your Radsystems Project - Tutorials - Radsystems Forum, you modify the quasar.conf.js file with your live URL and then save it. Then you have to open the frontend folder in a command prompt and run the following command to build to android.
quasar build -m cordova -T android --debug
for testing, produces an APK file that is not production worthy.
OR
quasar build -m cordova -T android
for production-ready files, that can be submitted to google.
Read more here Publishing to Store | Quasar Framework and here Mobile App Build Commands | Quasar Framework