How can i get the latest Firefox subscription

Hi

I am sorry, but Firefox is currently unavailable for Kindle devices.

Not sure if still possible but you may be able to side load install the Firefox apk on Kindle tablets. https://archive.mozilla.org/pub/fenix/releases/142.0.1/android/

Mozilla tried to get Firefox on Amazon app store a long time ago but Amazon was modifying the file which caused problems in updates and this has not changed since.