If TuneIn is set to your default, try saying “Alexa, play CBC Radio One”. TuneIn should play your local CBC Radio One station. Make sure not to say “CBC Radio” or “Radio One”, this will trigger a different radio station entirely -say exactly: "CBC Radio One".
CBC Music live stations are not available on TuneIn currently.
For podcasts, try saying “podcast” along with the show name when you ask for it. For example “Alexa, play “Someone Knows Something” podcast” should give the correct result.