WP Multisite sites are not working

Hi, I've followed the setup instructions to enable WP Multisite here: https://fussfreehost.com/

The issue is that the sites I create don't work - I get this error every time: "Oops! Google Chrome could not find <domain>"

For example:

I've checked the wpconfig.php and .htaccess files to ensure they're correct - and they are.

What else could be creating this problem?