@SharonBender -
What student Id or number are you talking about? The Canvas id for the student is included in the download. All of my bulkdownloads are in the following format:
studentName_12345_123456789_assignmentName
Where studentName is the students lastNamefirstName (all run together like doejohn),
12345 is the students canvas id and 123456789 is I am assuming the canvas file id for their submission
and of course assignmentName is whatever the name the student used for their assignment.
the canvas id is unique to a student. if that is not the id you want, you should be able to easily create a table matching a canvas id to a student id. At my institution, when I export the gradebook, I have a column for the canvas id and one for the students school id number(maybe this is the number you want). I could easily from that download leave those 2 columns in a spread sheet to have that lookup.
if it is indeed the schools student id that you want(and you don't see it in the gradebook export) then you should be able to get your administrators to add that field into the gradebook as a hidden field that comes with the export.