Hi @Jakob Søndergaard Frederiksen9 !
I hope you don't mind that i answer to you in English, as unfortunately I don't speak Danish.
From the error message that you're getting, I believe you need to create an app password in Exchange, so that you can complete your authentication to sync your calendar with Pipedrive. Check out this article to see how it's done5. Also make sure to click the "Help" link at the end of that message, as it may have important additional instructions.
Hope that helps! If the issue persists after doing the steps above, please reach out... (More)