Retrieve an export

Retrieve a CSV export job by its ID. When status is completed, download_url links to the CSV and download_expires_at gives the link expiry in epoch seconds. Before completion, and for failed/expired jobs, download_url is null. Exports support a maximum 31-day window, 100,000 records and 100 MB. Five jobs may be active per key. Files remain available for seven days; links last at most ten minutes. Only the creating key can retrieve the job.