Welcome to the Community! We hope you don't mind us answering in English as this is the official language of the forum.
We get that you're having hard times to invite a member for your Duo plan. Let's try to help here. First off, make sure that the invitation link has not expired, as they have a limit of 24 hours and you might need to send another one. Your member can also try opening the link using an incognito window of their web browser, as this helps to prevent cache-related issues. For more info, please consult the article here, which will give you all the needed steps to invite your partner to your Duo subscription plan.
Hope you find this useful. Keep us posted if you have any questions.
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