Hope you don't mind us replying in English, it's the official Community language!
Could you take a look if the same error appears when they try opening the link via an incognito browser session? Adding to this, please make sure there's no VPN connection enabled. The most sure-fire way to go about the verification process is to also use a desktop PC with a LAN internet connection.
It's also worth it to check your country settings. If they are not the same to begin with, they may cause the abovementioned error. Hope this helps!
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