If you need to activate iHeartRadio on your TV visit iheart.com/activate. If you're not currently logged in you'll be prompted to log in to your account first before entering your activation code.
If you're being asked for a zip code or the app looks like the screenshot below, you're using an older version of iHeartRadio. To see a list of VIZIO TVs compatible with iHeartRadio, please visit the VIZIO website. If your model is listed you may need a firmware update to your TV before you're able to use the latest version of iHeartRadio.