There are a number of options for embedding an iubenda privacy policy but here's the gist if you'd like to use their default button:

1. Create your iubenda policy and navigate to Step 3 - Privacy Policy Embedding 
2. Scroll down to the section Integrate the Policy and click Embedding Code. 
    
3. Copy that code and paste it into Unbounce using the Custom HTML objects tool. 
   
   

Ta-da! 

That will embed a button on your page that should automatically open your privacy policy in a lightbox.