Here's the link:
Doesn't work on Google Chrome.
I clicked on the (?) icon within Outlook that stated "Use Adobe Send & Track".
Sorry for the delay in response.
In case you haven't found a solution to this issue yet. Would you check if you are logged-in on Adobe "Send and track" Adobe Send & Track for Outlook, Acrobat .If not try logging-in and restart Outlook, try again.
Let us know if that helps.