Editorial use is, when you write an article and use stock images to illustrate it. They are mostly always unmodified. So yes, I would say from what you told that a credit is mandatory here.
(Disclaimer: As always with licensing, this is my interpretation of the rules. I think they are correct and advice is based reading and interpreting the license terms and on fair use for both the buyer and the artist/stock company, but I can not rule out that my interpretation is wrong. I'm not an Adobe employee)
ABAMBO | Hard- and Software Engineer | Photographer