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.
You will be given your share page URL after you create a share page.

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
Just paste your ShareProgress into ActionKit to set it as your after action page.

Don't forget to save your petition!