In order to setup Google Tag Manager tags for Klaviyo, we'll need to have a Klaviyo Public API Key

Step 1: Sign in to your Klaviyo Account

Klaviyo Account Link

Step 2: Select the Account dropdown on the top right-hand side of the page > then select Account

Step 3: Click Settings > API Keys

Step 4: Your Klaviyo Public API Key will be located under the section titled Public API Key / Site ID

Your Klaviyo Public API Key will be 6 characters long. Example: AAaAa1