I am in the US, and you're right that the link works just as you say. Of course, I have yet to access that link from within the site, only from an external link, like Google, or the one you added. Correction: I just found a link almost all the way down at the bottom of the home page - it's a Tux logo. But down at the very bottom of the page, there are links for other OSes (Win/Mac/Android), but no mention of Linux. It's like they either don't care, or don't want you to find it while looking around the site.
I guess one has to be pretty careful that they are purchasing NOD32 for Linux, not for Windows - same name, but apparently a different license... but not really because they say the "License can be transferred to Windows or macOS operating systems." Maybe it's an IQ test, and I failed. Silly me, I just wanted some protection for my computer.