Error installing plugin Visual Composer

Hello,

I’m trying to finish installing Highend but when I try to install Visual Composer I get this:

The plugin does not have a valid header.

Downloading install package from http://hb-themes.com/repository/plugins/js_composer.zip…

Unpacking the package…

Installing the plugin…

Destination folder already exists. /hermes/bosnaweb03a/b1700/ipg.youngforlifenet/drbobporzio.com/wordpress/wp-content/plugins/js_composer/

Plugin install failed.

I found the same issue in other posts but the answers all seem to be private.
Thanks,

Bob