Problem migrating Scalar book from one Reclaim site to another

I am trying to migrate this Scalar book on another Reclaim site:

To my Scalar installation on my Reclaim site:

When I try to do it through the Import URL, I get this error:

There was an error resolving the Save API URL

I have also tried downloading the RDF-JSON file from the original site and uploading it but am getting the same error message.

Can anyone assist me with this?

Thank you!!