For those on Android, I just downloaded it too. It doesn't come up in the Play Store, where I had hoped I could try it on my already existing reader, so I downloaded the Kindle app from there instead for free. I initially tried to download the book through Kindle itself, hoping to skip a step. It did come up on Kindle, but said it wasn't available in my country (which is interesting since it was published here in the UK, I assume). I then clicked the link to go to the full amazon.co.uk website direct and did a search there, where I downloaded it with no trouble to the Kindle app.
Just thought I'd give some of the steps since I hadn't used the Kindle app before and thought I'd explain in case there was anyone else in the same boat.