I have tried on several computers, and none have issue. The FixPak is just like the main mod, in that you must be logged into SubSim for downloads, and SubSim.com must be white-listed in your browser. Notice the top of the download pages that Onkel Neal has
If you are experiencing trouble downloading, it could be due to an ad-blocker or extension in your Chrome browser.
Try
turning off the ad-blocker or whitelisting www.subsim.com in your ad-blocker extension
or switching to
Microsoft Edge browser or Firefox to complete the download. Thanks.
So it could be that also... Let us know how you get along!