No WP Popup tab appearing

Hi there,
I have followed this tutorial: http://websitetrafficincreaserguy.com/mailchimp-popup-wordpress-actually-works/…
…so followed the steps as they go there.

I entered the API key and the List ID and saved, and then moved onto Step 6 and I was hoping to start working on the popup, but no ‘WP Popup’ tab has appeared.

I have re-installed but it hasn’t appeared. Is it somewhere else, or is there another fix for this?

Thanks,
Niven

https://wordpress.org/plugins/m-wp-popup/