Create a folder when file download from my app on internal memory root directory

Ionic Framework ionic-v3
#1

I’m try to create a folder when file download from my app on internal memory root directory like whatsapp , facebook or any others app but i did not get any solution. my file is stored in this location file:///storage/emulated/0/Android/data/my_app_name/files/abc.something

but I want to download file into my internal memory root directory .How can i do that.
I’m try to do like this below my code

download(event,item){
this.presentToast('Download started..');
	this.platform.ready().then(() => {
	this.storageDirectory = cordova.file.externalDataDirectory;
	const fileTransfer: FileTransferObject = this.transfer.create();
	let getUrl = this.selectedItem._meta_video_status
	let downloadFileName = getUrl.substr(getUrl.lastIndexOf('/') + 1); 
	//const imageLocation = `${cordova.file.applicationDirectory}www/assets/img/${item}`;
	const url =   getUrl;
	var URL = encodeURI(url);
	this.loading = this.loadingCtrl.create({
		content: 'Downloading...',
	});
	this.loading.present();
	fileTransfer.download(URL, this.storageDirectory + downloadFileName).then((entry) => {
	this.loading.dismissAll();
	this.presentToast('Download complete !');
}, (error) => {
			this.presentToast('Download faild, please try again !');
			});
		});
}

Please help me out I spent more than 20 days on it but did not get any solution.
Thanks

#2