URL Split test for VWO - Conversion tracking
 

I have 2 URL Variation pages (VSLs) that has an Add-to-Cart button which links to Clickbank's order page.

Question - How do I use VWO to track the conversion? I've already copied the code and put it into the 2 VSL variation pages but the conversion (purchase) doesn't happen on that site, the user clicks the Add-to-Cart button and goes to the order page, and the conversion happens there on the order page.
And I don't have any control over the order page so can't put any tracking codes there.

Does anyone know how to overcome this? I can ofcourse base it on the clicks to the order page but that doesn't guarantee there was an actual conversion.

Thanks,