Add Post to a Category

Hi, and thanks for any assistance on this question:

Overview

We receive posts automatically from a external source. As part of our workflow, a subset of those posts need to be added to a unique category.

I can filter out posts within the subset because they have a specific phrase in the title (so I can create a trigger by using [post title contains “xxx”])

Issue / Question

I don’t see any way to add a post to a category in any of the actions. Is this possible?

Thanks much!