Not sure why that is, it's just hosted on mega.nz. Link works for me too, perhaps your ISP is restricting access to mega.nz?
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My ISP doesn't restrict it, it says it for both Kingdom of Subversion and the Solarion Project. All my other games work through the launcher a ok, and I managed to get to version .20 with Solarion Project and .11 with Kingdom of Subversion, it just wont update them to the new versions claiming the previous 'Hosted by incompatible 3rd party website. Sorry if I shouldn't be asking you busy people this, I just do not know who to talk to regarding this issue.