No, that's automatically selected for you. :) Try using the website yourself.

The billing page clearly says "Subtotal $XX/mo"; the only place it says 'annual plan' is in the top box, which says 'Annual plan, paid monthly'; and when you select, eg. the standard photoshop plan, and click 'Buy now'; it takes you to a page where there isn't even a monthly option, despite the main page saying "US$9.99/mo".

As no time do you 'opt in' to an annual plan, except by clicking on the button that says 'US$9.99/mo'.

It would be 'obvious' if it said: You minimum commitment over 24-months is $$$.

It does not.

I don't know what you get from stubbornly refusing to acknowledge this is a dark pattern; clearly other people find this surprising too, and... well, I don't know what to say. Sometimes you have to acknowledge that you're wrong.

This is bad behaviour on the part of adobe; it's not really a he said/she said/my opinion is kind of thing; in many places, having the minimum total commitment displayed on the billing page is a legal requirement. In others, a no-penalty cancel-subscription is a legal requirement.

Adobe just flat out does neither unless you fight with them and threaten legal action.

I honestly don't know how they get away with it.