Hi,
Can you please be more specific next time? How is your current category listing right now? By the way, you are talking about the "Category Module" that you see in the left hand side sidebar in the Live Demo, right?
You installed the MaterialMart by following the TUTORIAL.PDF, you uploaded all the available folders from the ZIP file to /html/ folder in your Joomla, and published the Flexible VM3 Template plugin.. right? Then you are all set..
Now, all you need to do is to find the "official" Virtuemart Category Module (that comes with Virtuemart AIO) and publish that module in the sidebar. That's it. You should get the same look.. MaterialMart template stylizes the official Virtuemart Category Module and makes it looks like how you see it in our Live Demo.
If still no luck, then publish the VM Category Module on any page, and provide me the URL of that page, so i can take a look at it.
Regards.