Plugins install error

I just purchased the Fortuna theme 2 days ago and installed the parent and child theme without a problem. However, it said that I needed to install necessary plugins. I went to the plugins section of the wordpress dashboard and 3 of the plugins keep giving me a 500 error when I try to install them. I’ve tried installing them through the WordPress dashboard and manually through ftp (unzipped the folders). The plugins are Visual composer, Parallax/Video Backgrounds, and Revolution slider. Any help would be appreciated.
Thanks!