I posted the original post. For the record and for the benefit of the helpful participants in this thread:
1. I had already set up a PIN on my account. This, however, was not activated and was sidestepped by this vendor.
2. I added NO additional charges or subscriptions. In fact, I did not even use the screensaver within which there might be additional chargeable options.
3. The item was clearly designated as FREE to add. Adding is different than advertising aka ‘ads’. And free is free. If there are charges, it must be clearly disclosed in plain language.
4. I note that since my post and your helpful observations, the item and many others have been changed by Roku to clearly reflect a $0.99 charge. To me this is a tacit acknowledgment that this was a mistake Roku is taking steps to correct.
5. As of this writing I have not received a refund for the erroneous charge.