The icon pack, also comes with a dark flavor to match darker themes, can be installed very easily on your desktop.
The following steps will guide you through it.
First, start by downloading the icon pack to your computer, download by right clicking on the file-name and click “Save Link As…”. Note, you may alternatively use XDG-URL installer in case it runs on your distro.
Next, extract the file and follow the installation instructions according to your preference.
Install Soft Gray For Single User
To install for ‘single user’ only, move the folder/s you want to install into ~/.local/share/icons. you may issue the following in Terminal to do so:
mv /PATH/TO/Soft-gray ~/.local/share/icons/
mv /PATH/TO/Soft-gray-Dark ~/.local/share/icons/
Install Soft Gray For All Users
The installation process for ‘all users’ is pretty similar to ‘single user’, only, the path is different and you’ll need to have root permissions at hand.
mv /PATH/TO/Soft-gray ~/usr/share/icons/
mv /PATH/TO/Soft-gray-Dark ~/usr/share/icons/
That’s it! To start using the icon theme open up “System Settings” from Plasma’s “Application Launcher” menu -> Go inside “Icons” and select the name of the icon pack you wish to use -> click “Apply” to start using it.