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.
That article is talking about FREE channels, i.e. channels you don't have to pay extra for, most of which are supported by including ads.
Hulu is not a free channel, it requires a paid subscription. Hulu has several tiers to which you can subscribe. The lowest and cheapest includes ads, the next up the latter removes the ads for the most part, and the third adds live TV (local channels and I guess a few other things).
Try signing out of your Hulu app on the Roku (click the link in the upper right corner of the screen then scroll down and click "Log Out"). Then log back back in. That might get you reset to the add-free version on the Roku.
Let us know how you make out.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T
I made a mistake: The account I was using this time is not an ad-free paid account. It seems ad-free when used on a computer because of ad blockers being used on the computer's web browser. Sorry about the confusion!