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.
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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
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Don't forget to save your petition!