One of the reasons why your Starter Templates import could fail can be storing the XML file. To import the template content, WordPress needs to store an XML file in the /wp-content/ folder. In this case, you might see an error that says something like this:
Looks like your host could not store XML file in /wp-content/ folder.
The reason for this could be that your host is offloading /wp-content/ folder to a third party server. This basically means that the content is stored in some other place, for example a cloud storage.
Since storing XML file is a requirement of WordPress itself, unfortunately, there is no workaround here.
You will need to get in touch with your hosting provider and see if they can disable offloading /wp-content/ folder to a third party server temporarily.