Problem with Import unity package

Hi everyone,
I am watching unity tutorials and sometimes there are assets exported that we can use. In the video the guy shows how he import it, but in my case I have an error/message that tells me that there is nothing to import.

I am using the latest version of Unity 2017.1.0p5(Mac) and when I try to import package:
Assets -> Import package -> Custom package

and the result is:

Nothing to Import.
All assets from this package are already in your project.

But that's...

Problem with Import unity package