Error: We can't create your email address until you verify that you own this domain
You will see this error message in your Office 365 from GoDaddy account, if you are trying to use an external domain email address for your email. This is any domain at another domain provider, or in another account. Even if it is another GoDaddy domain, if it is in a different GoDaddy account, it is considered external.
Verify your ownership of the domain, in order to proceed with your Office 365 setup.