Followers campaigns present people with ads suggesting they follow your account in several places such as home timelines, search results, and the “Who to follow” section. Tweets are not required to run a followers campaign, as it is possible to show up in other sections (such as the “Who to follow” section) without adding Tweets to your campaign.
While not required, it’s a good practice to include a Tweet to let potential followers understand your brand more clearly. You can either create a new Tweet that will describe why people should follow your account, or select an existing Tweet. Additionally, not including a Tweet for your followers campaign can limit the reach of your campaign. If you’re going to run a followers campaign, maximize the reach potential with the available features!