Can you please explain what you mean by; recurse the D column from the last cell up to the top (or the first cell with a manager name) and gather all the manager names in an array.
Do you mean to filter out managers in Excel to get a list of all managers?

Recursion is the process a procedure goes through when one of the steps of the procedure involves rerunning the entire same procedure.

How do I gather all the manager names in an array in execl?

In computer science an array is a data structure consisting of a group of elements that are accessed by indexing.