Expensify API Downloader method

I am developing an API integration with Expensify for a client and am trying to understand where the actual contents of the CSV file are returned in the Downloader method. My client has configured a report called UserActivity in the templates section and I am now calling
which returns the name of the temporary file generated, for example exporta541733a-738f-4ffd-
9fd9-126ea4df9d7f.csv'. I then make the request with this JSON requestJobDescription:
{
type: "download",
credentials: {
partnerUserID: credentials.partnerUserID, // Replace with your partner user ID
partnerUserSecret: credentials.partnerUserSecret // Replace with your partner user secret
},
fileName: 'exporta541733a-738f-4ffd-9fd9-126ea4df9d7f.csv',
fileSystem: "integrationServer"
};
I am only getting the name of the original template in the response: 'UserActivity.ftl'. What am I missing here? Is the file going somewhere else in the response?