To use the tool, you need the following access: Viewer role for the Universal Analytics property Editor role for the Google Analytics 4 property After you've installed and activated the Google Sheets add-on (below), follow these steps: Import audience definitions from your Universal Analytics property to a Google Sheet. Decide how you want to export audiences from your Google Sheet to your Google Analytics 4 property (e.g., using the existing definition or modifying the definition first in the tool, then exporting). Export your audiences from the Google Sheet to your Google Analytics 4 property.
Seems simple enough. With a lot of power/flexibility to make any changes in between the import and export steps.