When you start creating a Convo Zap, you will be prompted to connect a New Account:
Click the button and a pop-up would appear. You would be then asked to enter your Convo Username and Password:
You would then be asked for Authorization to let Zapier access your Convo account:
Once you click "Allow Access", the pop-up would disappear and you will see the Convo account added to your Zapier account and is ready for selection.