Hi, I'm Elise, an independent advisor and I'd be happy to help with your issue.
From this error you have supplied it looks like, as the message says, the previous version on Window was not activated prior to it being upgraded to Windows 10.
You would either need to obtain the product key for the previous version if it was a retail version, and enter this here to activate.
If it was a pre-installed version then restore the previous operating system, activate then upgrade.
Or purchase a valid Windows 10 key.
Kind Regards,
Elise