You'll need to add a number in your TARS account before you can configure any chatbot with the WABA number. Refer this article on how to do it: https://help.hellotars.com/en/articles/4130801-how-to-add-a-waba-number-in-your-tars-account
Once you have added a WhatsApp number in your account, you can configure any chatbot at any point in time with the WABA number. You just need to select the chatbot ➡️ Go to distribute/share ➡️ select WhatsApp and select your number from the drop down of all numbers added in your account.
Once done, you can test it out by sending a WhatsApp text to the number.
You can check this on how to configure the number with a chatbot: https://help.hellotars.com/en/articles/5172351-how-to-configure-a-waba-number-with-your-tars-chatbot