I see you are both from Denmark and I also have a couple of users from Scandinavia with a similar problem, which is strange:
- The installer code is quite simple: if the activation key you inserted doesn't start with an "A" ( all current keys used since 2019 all starts with an A ), it assumes you are using an Esellerate legacy key, that's why it says "using a legacy key" but, since in fact it's not a legacy key, will surely fail.
Is it possible, because of keyboard or regional settings, that your "A" is not really an "A", possibly the "Å" ?
See this post here as well:
http://www.fsdreamteam.com/forum/index.php/topic,27359.msg179501.html#msg179501