Weihao Luo2,703 Points
The package could not be installed. The theme is missing the style.css stylesheet.
I downloaded the project zip from website and uploaded to wordpress directly.
So what is the problem? There is no another zip inside the project zip.
The project zip file doesn't need installing as such. You'll need to extract the zip file and then move the theme in to the wp-content > themes folder. You can then choose this via the WP admin.
If you're looking to install a downloaded theme you'll need to follow the steps here.
Hope that helps :)