Help getting started with Roku devices, including setup, connecting your device to your TV, linking a Roku device to your account at my.roku.com/link, adding channels, subscribing to services, and more.
Have you tried checking in your Spam folder as well as doing a search in your email? Customers have reported finding the activation email when performing those steps. We would also recommend trying to send the activation information to an alternate email address, the activation email link does not have to be sent to your Roku account email address.
If you are still unable to resolve the issue, please send me a PM with your Roku account email address, and include the serial number on the Roku device. I'll be able to assist you further from there.