I can save some data into file
val byteArrayOutputStream = ByteArrayOutputStream()
byteArrayOutputStream.writeTo(openFileOutput("FILENAME", Context.MODE_PRIVATE))
val data = byteArrayOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
byteArrayOutputStream.write(data)
byteArrayOutputStream.close()
But I want to save it not into my app directory, but into some shared folder.