CiviVisualize example graphs and visuals are not showing up
This is likely a problem in how you have incorrectly set up the extension url in civicrm.

To work, this (and many other) extension need to be able to load additional resources, javascript or images, and you need to configure civicrm to tell which url to use. (under /civicrm/admin/setting/url )

what is the right url to put there depends on where you have put the extensions folder, but on the good news, you will need to adjust your setting ones and it will work for every extension