You don't have an on-call schedule set up in PagerDuty, so Zapier won't be able to announce upcoming shifts without first configuring the integration with your account. To start, you'll need to create an API access key within your PagerDuty account by logging into your account and clicking on Integrations in the top menu, then selecting API Access Keys, creating a new one, saving it to a password manager, and entering it when connecting PagerDuty to Zapier. Once connected, you can create a schedule trigger that runs every week, specifying the day of the week and time for your Zap to run. You'll also need to add an action step which is a search step that finds users on call in PagerDuty, configuring the search parameters such as start and end times, and setting whether the Zap should be considered successful if nothing is found. Finally, you can add a notification action that sends a message to your team chat app, customizing the message text with dynamic values from previous steps in your Zap.