No value was entered in the SourceUsername field. If you are an administrator of the selected configuration set, you can ...

No value was entered in the SourceUsername field.  If you are an administrator of the selected configuration set, you can remove the SourceUsername field from the unattended setup file or type a valid account in the Sourceusername field. If you are not an administrator of the selected configuration set, you must type a valid user account in the SourceUsername field.  After you have updated the unattended setup file, run Setup again.