To install Widgetkit, you can either set up a theme demo package that includes Widgetkit 2 – currently, these are themes starting from January 2015 – or you can manually install Widgetkit in your CMS.
If the installation does not work this way in WordPress, you may want to try to install the Widgetkit this way:
Download the latest Widgetkit version and unpack all files to a local directory called widgetkit.
Using FTP, upload this directory to the /wp-content/pluginsdirectory of your WordPress installation on your server.
Go to Plugins » Installed Plugins in the WordPress administration and Widgetkit will appear in the overview of all available plugins.
Click on Activate to activate the newly installed Widgetkit plugin.
If the installation does not work this way in Joomla, you may want to try to install the Widgetkit this way:
Download the latest Widgetkit version and unpack all files to a local directory.
Using FTP, upload this directory to the /tmp directory of your Joomla installation on your server.
Go to the extensions installer in the Joomla administration, use the "Install from Directory" option to set the directory of your uploaded Widgetkit files.
Click on the Install button and Joomla will install it from the given directory.