Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
I'm making a guess, but it's likely that Amazon isn't supporting Roku devices in your country. They may offer Prime there, but they have to authorize their Roku app for that country. It sounds like Amazon hasn't done that.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
As @atc98092 mentioned, Amazon has not currently made the Amazon Prime Video channel available in your location on the Roku platform. Each channel provider determines the locations in which their channel is available in the Roku Channel Store. We'd recommend reaching out to Amazon Prime support to inquire further and share your interest in seeing Prime Video available on Roku in your location.
We're always looking to expand our presence, and appreciate you getting in touch!