You need to upload your file to the internet and link the QR code to the link (url) of that file. Use a free upload service, upload your file, take
the URL and create a QR code for that URL. When scanned, you'll be redirected to that file URL and download should begin.
This site: www.qrstuff.com... will help you to link different data types.
I haven't worked with qr codes but if you use a url such as
file://C:\full_path\to\file.ext
the file will be opened with the browser, which may prompt you to download or open, or just open it depending on file type.