The mentioned page lists the more useful information, which PDF variant is required. It is essentially pdf-a, whereas PDF/A-1a is the most preferred one.
However, having doubts that pdflatex is smart enough to add document structure, you might have to rely on PDF/A-1b, or PDF/A-2b. In any case, you will have to provide sufficient Metadata.
A standard way to create PDF/A is using Acrobat Pro (not Standard, not Reader), and there use the Preflight tool with the standard fixup to create PDF/A of the variant you can do.
Other suitable applications would be pdfapilot by Callas Software, or the 3Heights PDF to PDF/A converter by PDF-Tools. You might also ask those vendors whether there are services available (assuming that you have a one-time need).
Edit/Update: Apparently, that system accepts non-archival quality PDF versions, beginning with 1.4. Therefore, a dedicated PDF/A generator would not be needed, but Acrobat Pro would do, and instead of using the PDF/A creation preflight profile, using a PDF 1.4 or higher profile would do; and if you know what you are doing, you could even use the PDF Optimizer, which (in Acrobat X and newer) is accessible via Save as optimized…