Hi
Every project has design associated with content. It contains CSS, JS, images etc which are used in components, templates. Also when you edit the page in design mode to choose allowed components, that information is also stored under design.
It seems the project you have created is not having design associated and hence the warning, project using default path for storing design information.
Designs are stored under /etc/designs. The path to the design to be used for a website is specified using the cq:designPath property of the jcr:content node.
Document link:- https://docs.adobe.com/docs/en/aem/6-1/develop/the-basics/designer.html#Using the Designer
Source L- http://stackoverflow.com/questions/36173729/aem-no-design-message-displays-in-the-error-logs
~kautuk
Kautuk Sahni