Kavin:
I just checked on my Ultra and it says it is available for free on Hoopla and Freevee channels. I was able to play on Freevee with no issue. Hoopla, I don't have installed, so I didn't try. There were also ways to pay and view, but no need with those other two being free.
Check to make sure you have one of those two apps installed and updated.
You can also either do a system restart or unplug the Roku for 30 to 60 seconds and see if that helps.