For the OP, I just looked at your document with my Mac and Firefox. For most web pages I can tell it to print a page, and in the lower left corner of the print box, select "save as pdf". For the link you provided this did not work. The document portion of the page is in a protected space. However I was able to capture excerpts from the article using "Grab" which comes with the MacOS, however, this is just a picture of the text in the current window.