I don't think I understand what you're trying to accomplish. Any chance you could provide more details, including screenshots where possible?
I understood that tableau can fetch data from files which are stored in the share point and tableau will not count the number of files in share point drive to create a own table data for tableau by itself to have a report which can show the count with respect to file names, file sizes, file uploaded dates(which is what I expected while raising this doubt) let me know if you still did not get my point.
If you think this type of flexibility might be added to tableaus capacity in future then please add this to the Ideas forum. If not please ignore.