The instructions were originally written prior to OPDS version 2.3 which introduced the GUI. Bypass steps 6 & 7 and the first part of step 8. You can then pick up again after this at the checking stage of step 8.
Good luck with sorting it out. The instructions do work, I set up my iphone, but I hadn't thought about the kindle (which I am still waiting for).
I still would like to know how to write a plug in for Calibre that will automatically update the catalogue when books are added.