What should come back from the operation?

Choose the operation based on the result you need. Combining files returns a document. Extract can return structured information about a PDF, which is useful when your app needs to read the document's contents. Check that the returned text or table matches the original, especially on complex pages.

What does Adobe count and what should you download?

Adobe uses Document Transactions as a usage unit and lists operation-specific limits, including page or file-size limits. Check your expected jobs against those rules. Save the input and the output you need for your records. Before sending real documents, check whether your organization permits using the hosted service.

How would you check a table taken from a fictional PDF?

Draw a source PDF with three rows and a separate list of the extracted rows.

Compare the source and result
Mark headers, values and row order. Keep an exception if a total or label differs.
Keep your originals
Draw where the original PDF, the output and your review record would be stored.