At first try to remove the app from emulator, or do wipe data.

To run your android app from './android' folder:

1. Open prebuilded folder in Android Studio. Be sure that all dependencies automatically will be installed. Usuallty it takes some time
2. Next step npx expo run:android
3. Now your app is running, make some changes in native directory, and apply run from android studio - then you get succesful build, with applied changes.