Do Creators have to post on every social media for a campaign?

No, Creators do not have to post branded content across all social platforms as a campaign requirement. As a matter of fact, brands often like to see Creators post on various socials, but not all. Each creator performs best on certain platforms and may even have a different tone on another platform. With that in mind, it is up to the brand to identify which social avenue they want to take when deploying a creator for a new campaign.