Hi schipper3019,
You can download the PDFs that you've stored on Acrobat.com to your hard disk, and then use whatever method you prefer to upload them to the Kindle (you can't go directly from Acrobat.com to the Kindle.) This article on Amazon.com may be helpful: http://www.amazon.com/gp/help/customer/display.html?nodeId=200375630
Best,
Sara