Error message may include "Fulfillment Error" and "download expired" or even "Check date & time."
Date, time, and time zone are very important for communication with ebook servers! On your device, access Settings and select "Date & Time." Check these:
--Time - must be exact as possible.
--Time Zone - should be US Central Time zone for Kansas users. Do not use the same GMT -6 or -5 zone with a non-US country or city name attached. Not all countries do Daylight Savings Time or do DST on the same schedule as the US. You may need to re-check the time after fixing the time zone!