Goals and funnel steps on third-party sites
You can track a goal or funnel step page only if it contains the Analytics tracking code. However, in addition to tracking goals and funnels on your own site, you may want to track them on third-party sites. For example, you might want to track activity on a 3rd-party shopping cart site and set goals on those pages.
If you refer traffic to a third-party page on which you cannot alter the code, then you can track the outbound link as a goal or funnel step. For more information, see how to track outbound links.
If you refer traffic to a third-party page on which you can change the code, then you can track traffic to that page. Learn more about Ecommerce.