Cannot see WP standard themes

You seem to have tried installing WordPress under https://minoan-properties.com when its actual url is https://minoan-properties.com.mocha3013.mochahost.com/

Did you try changing urls after you installed WordPress?

https://www.minoan-properties.com is currently a working site which cannot be taken down until its replacement is ready. The replacement is to be built in WordPress, on a different server. The idea was to build the new site, and once ready simply point the DNS at the new servers.
So, after installing WP with indeed the https://www.minoan-properties.com URL, we added define WP_HOME and define WP_SITEURL, both with https://minoan-properties.com.mocha3013.mochahost.com/ to the wp-config.php which allowed us to finalise the install and start working, or so we thought. The result is as described above. I would have thought this would work, or am I that far off the mark?

You need to continue using https://minoan-properties.com.mocha3013.mochahost.com/ until the final domain name can be correctly re-directed to the new site.

yes, indeed. We cannot take down https://www.minoan-properties.com or change the DNS now. That would be ideal, but it is the owner’s livelyhood, so we can’t do that.

Change the urls back in the WordPress site.