minSdk != deviceSdk

For some reason, using 'L' as the targetSdkVersion makes it so the minSdkVersion is ignored. You should set the targetSdkVersion to something other than L.

It's not a bug. It's a feature :).

If you compile against a preview platform, you can only run on a preview platform.

You should set targetSdkVersion and compileSdkVersion to API 19.

You can read more about this problem here:

Issue 72617: Android Studio Compatible: No, minSdk(API 20, Lpreview) != deviceSdk(API 19)

Issue 72453: Setting sdkCompileVersion to 'android-L' creates an apk with 'L' as minSdk regardless of a lower minSdkVersion value