If you want to use the embed code we provide on AdForm as third party here's what you need to do:
1. First get the embed code from Bannersnack.
2. Visit this URL and encode the link you want to set on the banner: http://meyerweb.com/eric/tools/dencoder/
3. Add this line inside the embed code as seen below: clickTag=%%ec1;cpdir=https%3A%2F%2Fwww.google.com
<iframe src="//cdn.bannersnack.com/banners/xxxxxxx/embed/index.html?userId=xxxxxxx&t=1484302296&clickTag=%%ec1;cpdir=https%3A%2F%2Fwww.google.com" width="300" height="600" scrolling="no" frameborder="0" allowtransparency="true" allowfullscreen="true"></iframe>
4. Add the embed to AdForm and your clicks should be tracked correctly.