To enable analytics integration you need either the Universal analytics or the Event tracking analytics code integrated.
Visit this link to add the google analytics tracking code to your website.
Simply go to the Analytics Integration plugin submenu to turn on the Analytics integration. There are two integration methods you can choose from:
Events Tracking (recommended) - Allows you tracking all sorts of events, such as input focus, live search, facet changes etc.. with customizable parameters
Tracking as Pageview - Tracks only the live searches, as pageviews
While the plugin tries to get your tracking code automatically, it is recommended to enter your tracking code anyways.