Error downloading csv file using REST API

[Anonymous]

I am trying to download a paginated report output as CSV using the REST APIs. I can successfully download the report results as PDF however it is not working when I am choosing to download the information as CSV. I suspect I might not be passing in the right values in the PaginatedReportExportConfiguration parameter.

I am first calling 'Export to File in Group' using the Group Id and Report ID as shown below:

I then check the status which shows the status of Succeeded.

Then I try to download the file, but I get this error 418 - Unsupported file type returned by PowerBI

The report is hosted in a Premium workspace. I am calling the APIs from a third party application by Appian. When I make this same calls from the Learn.Microsoft.Com REST API, it works. Any idea what is the problem with my calls?