Connect your ActiveCampaign account to Hello Audio at https://app.helloaudio.fm/integrations. Click "Connect" under ActiveCampaign and paste your API key and URL.
Generally, you can find the API details in your AC account here:
Click the Settings gear at the bottom-left.
Click Developer and find your API URL and Key.
Copy each and paste into Hello Audio to connect the integration.
You can read ActiveCampaign's instructions here: https://help.activecampaign.com/hc/en-us/articles/207317590-Getting-started-with-the-API#how-to-obtain-your-activecampaign-api-url-and-key-0-2
Set up an automation in your signup page by following these instructions. You can add a listener to your email lists in ActiveCampaign, or tag the listeners in AC. You can also remove them from lists and/or tags. Set up a separate automation for each action you'd like performed on the contact in AC.
Watch the 4-minute video walkthrough here: