I am working with a client that uses a font that is not available to me. How do I get this font without changing my plan?
Is it a Typekit font? You need to subscribe to Typekit to download it.
Is it a typeface available for purchase? If so, you can buy it. Make sure it's the same version as your client.
You posted to Acrobat, though, not InDesign or Illustrator or Photoshop. Why do you need to have the typeface? Is it to make edits in the PDF? If yes, is the font properly embedded?
What is the issue you are having that you think you need the typeface?