Recital 32
Silence, pre-ticked boxes or inactivity should not therefore constitute consent.
http://www.privacy-regulation.eu/en/recital-32-GDPR.htm
Cookies critical to the site's purpose (login info, theme chosen, the cookie that records your consent to all other cookies) don't need tick boxes. The rest do.
I don't know why ad companies are spending money on solutions that are only "slightly" breaking the law when it's inevitable they'll have to pay someone to update it later on.