A “PDF QR code” is almost always a URL that happens to end in .pdf. Phones open the file in the browser or a viewer. That is how restaurants share a 12-page wine list without reprinting table tents every week.
Keep the file under a few megabytes on cellular. If the brochure changes, either replace the file at the same URL (best) or use a dynamic QR code and point it at the new file. Do not encode the binary PDF inside the QR - it will not scan.
FAQ: PDF QR Code Generator
Can I upload a PDF here?
This QR code maker encodes a public URL. Upload the PDF to your website, Drive, or Dropbox, set the link to anyone with the link, and paste it. If the file URL will change, sign up free and use a dynamic code so the printed square stays the same.
Google Drive links?
Use the “anyone with the link” view URL. Preview links that require a Google login will fail for guests.