You can check export failures in this column of your "Extract Data" Section.
Now if you click on the file which shows "failed", you would see a red dot on the button on the top right corner
Click on the "Workflow Run History"
You can see the Error Log.
If you are unable to debug the error, reach out to firstname.lastname@example.org
If you want to retry export, you can click on the Retry Export button as shown below: