FPS Tutorial Issue

On the FPS tutorial I try to import the mainLevelMesh but all I get is error NullReferenceException: Object Reference not set to an instance of an Object. How can I fix this?

I am using Unity 3.5.2 and downloaded the zip file FPS_Tutorial.zip that is 70.8M, Was this the correct folder or are they all required?

Any help is much appreciated.

You do not need to have the FPS tutorial download to make the FPS.

I have downloaded the zip and exported it into a folder and then imported it into unity and it has the error. Is there anything else needed before I import mainLevelMesh?

Thanks,