When you first try to use Propeller with Zapier, you'll need to connect to your account. To do that, click Connect an Account:
You should see a screen that looks like this.
First enter your email address. Then you'll need to generate an API key (if you haven't already). Follow this link:
Then click the Generate new API key button:
Copy the key and return to the Zapier tab
Then return to the Zapier window and paste, then click Yes, Continue:
On success, you should see: