SureCart's default behaviour is to redirect users to the dashboard upon completion of a purchase. You can override this behaviour using a custom checkout for your post access types and a custom thank you page:
The Following two help articles will help you:
https://surecart.com/docs/order-confirmation-shortcodes/
https://surecart.com/docs/custom-thank-you-page/
From Version 2.0, we have a method for you to display a link to the post directly built into the page, i.e so it looks like this
On your thank you page, you just need to add [view_purchased_post] to be able to display that link where you want on the custom thank you page