This post is part of the In Microsoft Dynamics 365 Business Central, how do I… series which I am posting as I familiarise myself with Microsoft Dynamics 365 Business Central.
When you sign up Dynamics BC you are also signing up to Microsoft 365 which comes with an Administration Center, some elements of which are used to maintain Dynamics BC. The Microsoft 365 Admin center is not available for use until you can prove you have ownership of the domain of the email with which you signed up to Dynamics BC.
Navigate to Admin Portal Home and log in if prompted. When asked if you are ready to be the admin for the domain, clikc the Next button: