You need to install the AmazonPrime App, you don't use a browser to watch AmazonPrime, at best it will only be in low res, Amazon will only stream in HD with the App.
If you need to create an account, and other account keeping activities, you should do that with another device, either phone/tablet or PC/Mac.
LG TV using Amazon Prime Video
in LG webOS Smart TV Questions
Posted
You need to install the Amazon Prime App, you don't use a browser to watch Amazon Prime, at best it will only be in low res, Amazon will only stream in HD with the App.
If you need to create an account, and other account keeping activities, you should do that with another device, either phone/tablet or PC/Mac.