Roku may have offers for the Apple TV+ streaming service, to be redeemed on Roku, in the Apple TV app. Roku will have their own terms and conditions for this. One offer per device. One offer per Apple ID. Requires Apple ID with payment method on file. For new subscribers only (that excludes current and prior subscribers). The offers and redeem end date may vary by country. The current US offer “one month free” of Apple TV+ ends 5/22/2024, i.e. redeem before that date.
Try contacting Roku Support for assistance with redeeming one of their offers.
Apple Support would likely also know about this offer, how it should work, but wouldn’t be able to rectify any issues in Roku’s redeem procedure, for the part that is processed on Roku’s systems.
I even received a 6 digit CODE where do I input it?
When signing in on a new device or other special occasions, a verification code for two-factor authentication may be needed, to be received on a trusted Apple device (or else a text message to a trusted phone number). The sign-in screen should then ask for this code with an input field.