The setup app defaults to a folder named aggMatch on the windows Desktop–that folder can be dragged to another location if desired.
The primary requirement is a MARC21 file. (MARCXML files must be converted to MARC21 exchange format; there are free apps that will do this).
The first time the app runs the 'Source file' box at the top will be empty. Click the ellipsis to the right to select a MARC file. (Each time a file is selected in this way it will be added to a dropdown list).
Press 'Run'.