[Closed] Struggling with Singletrack Kindle download

I'm trying to download the magazine in Kindle format but when I click on the download link I get "Invalid File Type" followed by the issue number .mobi. I'm on a mac and tried in Safari and Firefox and also on iPhone with the same result every time.

I've also tried directly on the Kindle using the "experimental" web browser but can't get beyond the front page ("there was a problem loading this page" on any link from the front page).

Any advice gratefully received.
Cheers.