The idea is to add a LINK after

%%(org-anniversary 2006 3 21) World Down Syndrome Day (%d years) <LINK>

So when I see it in my agenda for that day, I can click and jump to a ORG heading in a ORG buffer where I can learn more about the event. I tried using C-c l (org-store-link), but it fails. Any help, thanks!