Two parts: connect CircularID to your store's REST API (for product mapping), and install the plugin (for the passport to actually appear on product pages).
Go to Settings → Integrations → WooCommerce, paste your site URL and the two keys, and click Verify & Connect.
Download the CircularID WooCommerce plugin (a single plugin, no dependencies beyond WooCommerce itself). In WordPress: Plugins → Add New → Upload Plugin, choose the ZIP, install and activate it. Then go to Settings → CircularID and paste your Organisation ID (shown on the Integrations page in CircularID).
The plugin renders the passport badge automatically after the product summary on every product page, by matching that product's SKU. Use the [circularid_passport] shortcode instead if you want to place it somewhere specific in your theme.
The generic embed snippet works in any WooCommerce theme too — paste it intosingle-product/after-summary.php in your theme, or into a Code Snippets plugin.