Clone repository or download compressed file and upload them to typo3conf/ext directory. Install extension using Extension Manager.
To make it work you have to include static typoscript provided by extension.
By default you will have to install VHS extension github.com/FluidTYPO3/vhs either from Github or TER to be able to run soee - Cookiecuttr without modification as it uses some viewhelpers for setting assets etc.
This extension implements jQuery CookieCuttr plugin cookiecuttr.com to easily use with TYPO3 CMS. All configuration details can be found on plugin author page.