First, make sure your device has the correct storage setting when using the app.  To do this, open the main app Settings, then tap Apps or Application Manager (depending on your device, this may look different).  Next, tap on our app and then tap on Permissions, then tap on Storage.  To turn the setting on, move the switch to the right until it turns green.  Next, press on a torrent, then press on Details, then press on Download Location and make sure it’s set to Download folder.