You dont pass the filepath or filename, the response in postman is the CSV report, you have to save the result as a csv file
GET 'https://mytenant.api.identitynow.com/cc/api/report/get/011b6d9f22854604857eda0894f9605b?format=csv' --header 'Content-Type: text/csv'
Result (example of “Certification Signoff Report”):
Name,Reviewer,Activated,First Action Date,Sign Off Date,Owner
Identity Access Review for Test Manager,,"10/23/23, 6:18:29 AM",,,Test Manager
Identity Access Review for TESTuser Hong,,"10/23/23, 6:18:29 AM",,,TESTuser Hong
Identity Access Review for David Zoom,,"10/23/23, 6:18:30 AM",,,David Zoom
...
Then in postman, you would copy the whole response body, and paste into notepad, and save as csv.
in a script you would save the response to some variable, then write that variable to file
responseBody = IDNAPI.get("#{$config['baseUrl']}/cc/api/report/get/#{report['id']}?format=csv")
writeToFile(responseBody.body,filePath,fileName)