Why are my texture pack materials completely blank?

Okay so I just went to the asset store and got Yughues Free Ground Materials. I only imported 4 different materials from this pack onto my unity account : dry ground pattern, grass pattern 05, ground and rocks pattern 02, and lava pattern. Once I got them I clicked on my 'All Materials' button and I'm looking at them and they are totally blank and only white. It said in the upper right corner of the screen 'Normal mapped shader without a normal map. Consider using a non-normal mapped shader for performance'. Also I am extremely new to Unity so I have no idea what this meant. Can anyone tell me how to use the materials that I downloaded without them being blank?