not working on Kindle Fire

I have uninstalled and reinstalled several times. Worked with Amazon for 45 minutes and they couldn't get it to work. What can I do? I do my studying on my kindle everyday. I click on the app. it downloads and I try to maneuver through the app and it just goes back to the devices home page.
Please Help!

same thing happening for me on Kindle Fire tablet

There was a 7.4.1 update that just went out on the Amazon Appstore to fix a crash.