Some workflow kits use Gumroad or similar checkout services for delivery.
Some links go to external checkout or tool pages.
When a page links to a product or tool, the destination may be an external checkout, tracked setup link, or a partner page that can return referral or affiliate credit.
Some tool links may be tracked setup links and can later be converted to affiliate URLs.
Links are added because they help the workflow or launch path, not because they are paid placement.