Looks Like Flickr has changed things around again (Whyyyyy!?!) ;-)
Anywho, here is how to download now... (It may seem convoluted in these directions, but
it really is much easier and faster to do than it sounds.) :)
Here's a summary of the steps:
1) Navigate to the main page for the image of the paper you want.
2) Scroll down through the description of the image until you see some icons
3) Click on the three dots icon: "..."
4) Choose "download all sizes"
5) A box with sizes will open, select "Original" & click "download"
6) Click "OK" to save the file.
Then just look around until you find a paper set that you like.