Kindle Fire HD 7″ (3rd Generation)
Kindle Fire HDX 7″ (3rd Generation)
Kindle Fire HDX 8.9″ (3rd Generation)
Those are the Kindle Fire emulators. They have been discontinued and no longer available to download.
Amazon has discontinued support for the HD and HDX tablet emulators.
You should follow the guidance at https://developer.amazon.com/public/support/submitting-your-app/tech-docs/02-submitting-an-android-app and https://developer.amazon.com/public/support/submitting-your-app/tech-docs/03-pre-submission-assessment-guide in order to optimize their Android apps for Kindle tablets.
https://forums.developer.amazon.com/forums/thread.jspa?messageID=9933&tstart=0