I can't add Amazon Prime Video channel to Roku . How can I do that ?
Where are you located? Problems like this are often due to limits on where particular channels are supported/offered.
India.
Unfortunately, the Roku website doesn't offer India as a choice in its country selector, so I can't see if it is in the channel store for your country. As such, this is probably a question for Amazon themselves. Make sure when you contact them, that they know you are talking about a Roku app working in India as they might otherwise assume you mean watching Prime via a web browser.