Creates an ad inside a TikTok ad group. identity_id is required (list_tiktok_identities); the ad runs under that TikTok account identity. Give exactly one creative source: tiktok_item_id (promote an existing TikTok post as a Spark ad; the identity must own the post), or video_id (an uploaded video) with ad_text and landing_page_url, or image_ids. For click-to-WhatsApp ad groups pass whatsapp_number (with country code) and optionally whatsapp_message; for Direct Message ad groups pass auto_message_id. call_to_action e.g. LEARN_MORE, SHOP_NOW, SIGN_UP, CONTACT_US, BOOK_NOW, SEND_MESSAGE. The ad is created paused. confirm=false returns a preview, confirm=true creates it.