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.
Acorn's website indicates it IS available in Denmark. That's the first part of the equation.
The individual channels provide their channel apps, Roku just provides the platform on which to run them. The second part of the equation is whether Acorn has provided Roku with a channel app that is coded to allow operation in Denmark. I'm in the US and don't have any way to determine this. If they have not provided one yet, you should be able to watch on a computer via a web browser.