Once your QR Code is ready and you want to download it, click the drop-down icon present adjacent to 'Download' option.
There you'll see the option—'Export as JPG'. Click on it and your QR Code image will be downloaded in JPG format.
If you want to download JPG image of a previously created QR Code, login to your Scanova account and go to Saved QR Codes.
Click the download icon for whichever QR Code you want and click 'JPG' option.