Hello Anne,
Based on translation:
"You do not have the correct permission level to complete this action. Please contact the ICT helpdesk." That's what I get as a pop up message when I want to create a folder, 📁 in my recently added account via IMAP in Outlook.
I'd recommend reaching out to the ICT helpdesk (I'm guessing that is the company you work for). You will need to get the necessary permissions to adding folders to the specified e-mail address you are trying to create it in.
If this is helpful please accept answer.