VK - VK authorization setup using oAuth protocol
VK.COM - Vkontakte authorization setup using oAuth protocol
Beforehand it is required to set up a plug-in. Manager of extensions => Manager of plug-ins => group of plug-ins "slogin_auth" => plug-in "Social Login Vkontakte auth".
Go here and create new application. Choose Web-Site, enter name, site address and base domain. On the next page get Application ID and Secret Key and enter them in corresponding fields in component settings. Save settings and enable VKontakte login.