AUP has set the prices on a per-journal basis from the outset instead of a price of all items of type Article across the site. So, the price needs to be set at journal level.
You can do this by going to the journal homepage and clicking on “Manage Prices for the Journal” from the left side tools menu. You can then click on “Create a new pricing/access rule” and then select “Any article within this journal” from the dropdown and “Download price” from the pricing models dropdown. This will let you set prices for the journal. You can select a publication date range or volume/issue range if you want.
There are options to set the price per journal, per issue, or per article (= all articles in the journal). We always do the latter.
Any access license (subscription, free, Open Access, see License) will always override the purchase options for that electronic content item.
So, if the license type tagging in the XML has resulted in an OA license in the database for the article, then the article will show as OA even if the pricing rule specifies a price for it. That is how, for example, the occasional OA article in a paywalled journal works