First create your ShareProgress page, then paste that URL as your "After-Action Redirect URL" in ActionKit.

After you create a page on ShareProgress, you will receive a url for your newly-created share page. Highlight this url and copy it on to your clipboard.

With that URL copied, log into your petition on ActionKit. Click on Step 3: After-Action information. Replace the default ActionKit thank you page with your ShareProgress page by pasting your url in Redirect URL

Don't forget to save your petition!