As for this integration, there are a few easy steps which you'll need to follow.
Navigate to your backend
Joomla > Extensions > Plugins Manager and then search for Content - Komento plugin. Please ensure this plugin is turned on.
Next, navigate to Komento's integration configuration page.
Joomla > Components > Komento > Integrations. Select K2 in the component list.
Next, Under the Workflow tab, make sure that Enable Comments is set Yes and set the categories assignment appropriately.
Navigate to K2's configuration page,
Joomla > Components > K2 > Comments. Turn the setting Global setting for comments to Enable for everyone, and you're ready to go.