https://www.amazon.com/Amazon-Digital-Services-LLC-Download/dp/B00UB76290
I don't think that the free Matt Bracken Kindle downloads described in this thread require Kindle Unlimited. It looks like the Kindle Unlimited deal for these books is already available, while the free downloads described in this thread will only be available in the near future for specific books on specific days.
Aha! Thanks.
And yes I did download the free version as well, on both PC and Android.