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.
It depends on whether it's Roku asking for your 4-digit PIN (which you or the owner of the Roku account would have set) or the app asking for a code.
Apps will generally provide a URL -- along the line of AwesomeService.com/Roku or StreamStuff.com/activate or something similar -- that you'd go to on a browser and enter. That's usually when you are logging in to the app after it's been added.
The 4-digit PIN is something you (or whoever set up or manages your Roku account) would have set.
DBDukes https://www.dbdukes.com/Roku Ultra (4660) Roku Streambar (9102) Roku Streaming Stick+ (3810)