The document goes through several states during processing:
PENDING: Document is queued for processing
PROCESSING: Document is being processed
COMPLETED: Processing finished successfully
FAILED: Processing failed
EXPIRED: Document has expired and is no longer available
Each time you call GET, new temporarly urls are created for downloading the files and they will expire after a certain period. Don’t store these URLs, instead store the document id, and call GET to generate new download URLs everytime you need them.