How do “External Page” conversion actions work?

When using External Page conversion actions, a conversion should be counted when users access the external page. However, Nelio A/B Testing has no access to pages outside your WordPress site. So how does this conversion action work?

External Page conversion action detects the user clicking on a link that might take them to the external page. Therefore, it doesn’t technically track the user “visiting an external page” but rather the fact that “the user is about to leave the current page in order to see an external page.”