Soon, you will no longer be able to download eBooks from Amazon.
If you have 3rd party devices such as the kobo reader or nook, you will be out of luck, unless you act quickly.
It is recommended to download your digital content (Specifically Books and Magazines) before the 26th. You will not be able to download Samples, Loaned, or Borrowed books.
You can do so manually via this site on desktop computers: https://www.amazon.com/hz/mycd/digital-console/contentlist/booksPurchases/dateDsc in a similar manner to downloading magazines.