Change of Account/Email

A colleague left the company and I (the admin of all accounts of our company) have to change the account of the former employee for a new employee .
I have made the change for the former colleague and she has confirmed the changelink email from Zoom! Nevertheless, the access for the new employee is not working! Why? Can somebody pls. help me...Zoom Support (chatbot) does not understand my request and my problem. So it can not be solved...