I've tried Internet Explorer, Firefox and Edge and they don't work. But Google Chrome does. I guess Whistler does not have a "broadcaster's mentality" (where they want to reach the broadest number of customers). It doesn't matter what's most popular, it should be coded to work with the largest number of browsers.
I had the same issue. I just recently purchased a new computer which uses Microsoft Edge instead of Internet Explorer. I had converted my Radio Shack PRO-668 to WS1080. Afterward, I could not get the proper buttons on Whistler's website to appear for downloading EZ Scan using Microsoft Edge. I downloaded Google Chrome and had no issues whatsoever getting the software downloaded and running.
I have always steered clear of Google Chrome for the fact that they insist you have yet another tool bar up there on the console bar. And, in so many software installations Google keeps adding itself onto everything, sometimes when you are unaware. I have uninstalled at least 3 instances of Chrome that snuck up on my desktop. Aggressive marketing is one thing, forcing something on you without your knowledge is something else. That Google Chrome bar install has goofed me up far too many times. Once I adjusted to MS Edge I like it ok.
It isn't a matter of which browser you use but how you use it. Nor must the browser necessarily be up to date. Their website is using third party Shopshare, part of Shopify to sort and select the download. The files are hosted on dropbox. So, if your browser is blocking third party content, blocking scripts, or any one of the third party content sources you will have trouble with the site. This goes for any website with such construction.
Their site works just fine for me in Firefox. I have script blocking and ad blocking. Scripts for shopify.com and shopshare.io must be enabled. Security defaults and/or user settings in recent Firefox versions may get in the way. Firefox for example detects and blocks tracking by default if you choose.