No contests on Google Plus
Unlike Facebook which allows competition but with very strict rules, Google Plus won’t let brands run contests on their pages.
However, a brand can post a link on its page in order to invite people from Google Plus to enter a contest hosted somewhere else (on their website or on Facebook for instance).
Consequently, Kontest competitions could not be installed on Google Plus pages. Fortunately, you can still install your campaigns on your Facebook page, your website and on mobile phones!