The number of Twibbon designs you can upload for a campaign depends on your account type.
Free Version: If you use the free version of Twibbonize, you can only upload 1 Twibbon design per campaign.
Premium Creator: If you subscribe to the Premium Creator package, you can upload up to 10 Twibbon designs per campaign.
To start subscribing to the Premium Creator package, learn more here.
You can also learn more about the Premium Creator plan here.