wp_cosmetics theme: problems during installing

I have download the template from Omega website.
But I had some problems during the theme installing. The following is installing process.

Unpacking the package…
Installing the theme…
The package could not be installed. The style.css stylesheet doesn’t contain a valid theme header.
Theme install failed.

Please kindly see the attached pictures and help me find out the reason and resolve this problem

Many thanks in advance!