I have Dish tv and on my Fire TV I can verify my Dish account. This allows me access to MSNBC and other content.
How can I do this with Roku?
On Roku there is no Dish TV app nor a MSNBC app to my knowledge.
So I dont know where exactly you cant verify your Dish account,
There are many flavors of NBC apps available.
MSNBC Live is available on a few Premium (paid) Channels
I had to go download the bravo app and verify with dish through it to access the MSNBC live stream