Already on the first downloaded sample code (“using files”) I got a build error from Android Studio 4.2.1:
“This project uses AndroidX dependencies, but the ‘android.useAndroidX’ property is not enabled. Set this property to true in the gradle.properties file”
But there is no gradle.properties file. The solution was to create one with that name in the project root directory, and add the content:
Thereafter the project builds and runs as described.