On initial setup, current Roku's ask for an email that they use to send the CORRECT links for setup. If you bypass and try to search or type in an address, and just use some suggested link, you will hit a SCAM site.
Roku has no real phone support, and are impossible to call. Why would Roku need your Amazon account? You ignored multiple red flags and deserved what happened to you. Sorry it sounds harsh, but that is the real world today.
If the Roku did not ask for email, then either it is very old (they went to email setup several years ago), or it was used by a scammer and returned.