I think I figured this out. When you start off on the main page for each
topic/subject, there are links to the exam guides. Those guides
represent the certification and (1) you can see the reference number in
the tab name and (2) the "Schedule your Exam" link is on that same page.
Sites start page https://express.adobe.com/page/t8ASQanIS7sFg/ click
exam guide, takes you to this page:AD0-E117 Adobe Experience Manager
Site Architect Master Certification --
https://express.adobe.com/page/O8ouF761ak...