Go to the Google Play Store and type primevideo.com/mytv
Click to Download button for Prime Video app.
You need the most recent version of the Prime Video app.
From the Prime Video app, select the Cast icon.
Your device must be connected to the same Wi-Fi.
After you download the app.
log in with your Prime Video account to watch.
Select “Sign in and start watching”.
Enter your Amazon account information.
Choose “Register on the Amazon website” to get a 5–6 character code.
Then sign in to your Amazon account and enter your code.
Then Find to search for the show or movie you'd like to watch.
Tap on the title you'd like to watch and tap Watch Now.
Your show will begin to play now enjoy.