Important! if you download the All Files archive from ThemeForest and try to upload it to your WordPress, you will receive this error: Theme is missing the style.css stylesheet. Please make sure you unzipped the main archive and are uploading the correct file to your WordPress.
When you are ready to install a theme, you must first upload the theme files and then activate the theme itself. The theme files can be uploaded in two ways:
How to Setup and Demo Import (Video):