Is the output really PDF/A?

It is PDF/A-2b preparation, and the difference is stated in the dialog itself. Fonts are embedded, the structure is tagged and the file carries PDF/A identification in its XMP metadata, but no ICC output intent is written, so a strict validator reports partial conformance.

Why does PDF/A insist on embedded fonts?

Because the format's promise is that the file renders the same in fifty years on a machine nobody has designed yet. A PDF that merely names Calibri depends on a font being installed then; a PDF that carries the glyphs does not depend on anything.

What is a tagged PDF, and do I need one?

A tagged PDF carries a structure tree: this is a heading, this is a list, this is a table with these header cells. It is what lets a screen reader navigate the document rather than read a wall of positioned text, and most accessibility requirements and archival submissions ask for it.

Does the file leave my device to be converted?

No. The PDF is planned and drawn in the browser tab, page by page, from the same layout the editor is showing you — which also means the page count in the PDF matches the page count in the status bar.

Can I password-protect an archival PDF?

You can encrypt the export, but do not do it for an archive. PDF/A forbids encryption precisely because a file nobody can open in 2075 has not been preserved. Keep the password for the copy you e-mail.

Make a PDF/A From a Word Document

Archive-ready PDFs, made in a browser: what PDF/A actually requires, what this export does and does not write, and how to check the file before you submit it.