I use rp.GetSafeDirDefaultExternal and file.DirRootExternal.
My manifest
B4X:
AddManifestText(
<supports-screens android:largeScreens="true"
android:normalScreens="true"
android:smallScreens="true"
android:anyDensity="true"/>)
AddManifestText(
<uses-sdk android:minSdkVersion="19"...