If you use the external account to access Azure AD, such as MSA account(e.g. outlook.com, hotmail.com), and the account from other Azure AD tenant. You may experience the error message as below.
There are two methods to resolve this issue.
Method 1
Log in to new Azure Portal by using the account with Global Administrator permission for Azure AD. Navigate to the Azure Active Directory extension, from the User settings tab, toggle the setting Guest users permissions are limited to No.
Method 2
Log in to new Azure Portal by using the account with Global Administrator permission for Azure AD. Navigate to the Azure Active Directory extension, from the Users and Groups tab, search for the external account, and change the Directory Role to Global Administrator.