A Google Category is mandatory

Hi,

I get this message “A Google Category is mandatory for each item in your Facebook feed. Please select a master category to proceed. You can also select sub-categories to be more specific.”
But I have no possibility to click anywhere and fill in the category.
I do get an error on top of the page that links to a product page.

What must I do to enable the product feed?

Thank you for your time and help.

Kind regards,
Dominic – Adespresso customer ??