Template messages need to be approved by WhatsApp team before you can send out to your subscriber list. You can learn more about WhatsApp template messages in this article: https://help.hellotars.com/en/articles/4870250-what-are-whatsapp-template-messages
You can add a template message from approval from the TARS dashboard itself. Once you add a number in your TARS account from the settings section, you'll be able to see a button of "Add a Template". Templates are added at the account level and will be associated with a number irrespective of the chatbot connected to it. You can send out the approved templates using any chatbot but should be the same number. You need to select the number from your Account Settings ➡️ WhatsApp and then click on add template message.
A window will pop-up where from where you can add the template name and the content.
Once added you will see the template added in the list with the status (approved, pending, submitted and rejected)