If you want to activate prime video on my tv then you need to follow some steps to activate this. First thing you should know, If you want to log into amazon prime video on TV for that you also need to log in to your phone.
First, go to www.primevideo.com/mytv in your mobile phone browser.
Then click on sign in button
Enter your registered mobile number or email address.
After that select the My TV button from the drop-down list.
After that registration page will be open, enter the registration code to register to smart TV.
For more details, Read: https://www.datarecovo.com/primevideo-com-mytv-activation/