The Microsoft Identity that we provide uses a SonarCloud application which will be “installed” into your Azure AD tenant. This will give SonarCloud access to your firstname / last name and email address so that we can register your in our system.
However if the account used to login to SonarCloud is a guest account (coming from another Azure AD and registered as such into the original one), then this scenario is not yet supported.
That lead me to think about this scenario given your error. Is that the case ?