Hi Karandeeps51149841,
Thanks for your reply, may I know following question first:
Why there are big differences between the counts of "Download Filename Instances" and "File Downloads (Custom)"?
Which one I should use as the "right" one for getting the times of a document is downloaded?
About the Activity Map in your reply:
When I validate in Omnibug, I can see the 2 "Download Clicks" are triggered when user click on the pdf:

In the 1st "Download Click"

In the 2nd "Download Click"

Then, it seems to me the activity map link does work.
Thank you again.
H