Order messages sent through the WhatsApp Business (Cloud) API must use a template Meta has approved. Pick a starting point, edit it, and this page checks it against Meta's approval rules for the UTILITY category, shows it as a WhatsApp bubble and gives you the JSON to create it. Free, no signup, nothing leaves your browser.
POST it to https://graph.facebook.com/v21.0/<WABA_ID>/message_templates with your access token, or paste the same fields in WhatsApp Manager → Message templates. Approval of utility templates usually takes minutes.