How can I match up the page numbers and the page labels with PDFpen for Mac?

Version 12.1 and later supports displaying page labels added to documents. PDFpenPro users can go a step farther with the ability to add or edit page labels.

What is the difference between page numbers and page labels?
Page numbers are numbers added to a document's pages and print with a document.

Page labels describe the numbering scheme of a document; Page labels are an aside and do not physically print with a document. 

Matching page numbers with page labels: 
PDFpen (regular version) will only display and remap page labels if page labels were already added to a document by another application. 

If the document has multiple page numbering schemes i.e. Roman or Arabic numerals or letters, but does not yet have page labels, you will not be able to search by the actual page numbers included on a document. 

PDFpenPro allows you to:
a) Add page labels to a document that does not yet have page labels, or 
b) Edit page labels for documents that have been heavily modified.