@faxlain, @now4dw, @damoweb
Here is some basic information about Imagick – https://en.wikipedia.org/wiki/ImageMagick
Briefly – it is image manipulation library for PHP, which is highly required, because low-level pdf-to-jpeg convertation works through it.
Imagick is a server software. Unfortunately, this means that Imagick itself cannot be included to the plugin, installed through the WordPress interface or WordPress plugins system.
To make it work, someone, you, your server administrator or your hosting provider, should install (or enable, if it’s already installed) this software on your server. If your site is maintained by some administrator, he or she already knows how to install ImageMagick and Imagick libraries. Otherwise the installation could be done through cPanel in some cases and you could try to install it.
Here are few examples of installation instructions (these links were just the first on top of the Google search results):
https://www.dreamcreative.net/2013/07/install-imagemagick-on-a-cpanel-server/
https://www.webdesignblog.asia/operating-systems/linux-os/updateinstall-imagemagick-centos-5-centos-6/
https://stackoverflow.com/a/18150533/741782
Sometimes your hosting provider could restrict installation of additional software. In this case you can contact them for further instructions and details.
If you have VPS (Virtual Private Server), the Imagick can be installed through the SSH and command line interface.
BTW – great documentation otherwise ??
Thank you