Internet Explorer doesn't support the download attribute.
Your best bet is to just host the data on the server-side and set the Content-Disposition header. If that is not an option, you might try using a data URL instead and set the MIME type to application/octet-stream, but I'm not sure if that will work.
I was not notified of your response and have just read it, after finding this solution independently and returning to post the solution. Thank your very much and it is a shame I did not read your answer earlier.
Barry's not gonna like this. Barry's not gonna like this one bit. What is Barry's deal with tiny ads?