Sorry for the delay in response.
Could you please try turning off the Wi-Fi connection and see if that works?
If it doesn't, try relaunching the app and see if that helps.
Try using the Export PDF/ Create PDF option in the app and see if you are able to tap on Sign in.
Awaiting your response.
I am having the same issue on the Kindle Fire HD 8 7th generation. I tried logging in from create document and export pdf, and nothing happens when you click on the text field or the "sign in" button.
Any help would be appreciated,
I'm having the same problem sign in screen inactive ??
Having same issue on latest Amazon Fire HD 8 7th generatioin