You can not share assets (with the sharing component).
You must first copy them to the external storage (eg: storage/emulated/0/Music) by using eg Taifun’s file extension. App Inventor Extensions: File | Pura Vida Apps
For this WRITE_EXTERNAL_STORAGE permission is required.
So ask for WRITE_EXTERNAL_STORAGE at Screen1.Initialize instead of READ_EXTERNAL_STORAGE.
Note: READ is automatically granted.