I am unable install Plugins that comes highend theme error 403

i installed the highend theme today and can not install the plugins
i have looked through the forums and see that a lot of people have had the same problem but the answer is always a secret which i do not understand as it is the weekend and now it seems i will not get an answer to this and will nor be able to do any work on my site
i spent hours on the phone with hostgator they had no idea what the problem was and it is very frustrating i just want to build my site i am missing…
Highend theme requires the following plugin: Visual Composer – Live Drag & Drop Page Builder.
Please install this plugin.
Highend theme recommends the following plugins: LayerSlider WP and Revolution Slider.

please can some one help me asap i really would like to start working on the site thanks
thanks Jo