A campaign needs three things: an active WhatsApp channel, an approved template, and contacts who can be reached on WhatsApp.
Channel
Broadcasting is WhatsApp only. It works on WhatsApp channels connected through Meta and through Bird. Instagram and Messenger cannot send campaigns because they do not support template messages. SMS is not included.
Template
You can only pick approved (or reinstated) templates from the channel's WhatsApp account. These template types are not supported and do not appear in the picker:
Carousel templates
Location templates
Templates with a dynamic link button (a URL that ends in a variable)
If the template has an image, video or document header, you upload one file and every recipient gets that same file. If the template has a fixed header file, that file is used.
Contacts
Each recipient needs a WhatsApp number or WhatsApp ID stored on the contact. The general profile phone number field is not used for sending. Blocked or opted-out contacts never receive a campaign.
Permission to message
Under WhatsApp policy, you are responsible for having permission to message your audience. Meta watches the quality of these messages closely, so avoid flooding inboxes.