Short answer: Netflix (and Disney Plus) cannot be installed on Fire tablets through Google Play Services . See
@Jumbo100 post #9,482 for a more detailed explanation by
@Datastream33 .
Essentially, your looking at the ongoing collateral damage from the aftermath of the 2017-2019 Amazon/Google corporate feud. As a consequence, Fire tablets are not Google "Play Certified" devices , so Netflix and Disney have decided not to be listed on Google Play Store and cannot be installed through Google Play Srrvices. Ostensibly for security reasons.
As a consolation (?), both Netflix and Disney plus can be installed from the Amazon Appstore and run absolutely flawlessly. LOL.
So much for the Amazon/Google infighting ...Bah!