Hello there, marisajmcbride.
I'd like to make sure we're on the same page. Are you in the process of adding a product that you'll be using for estimates? If so, you will need to manually add the category for each product since adding it quickly is unavailable.
I'm adding this article for reference: Group your products and services into different categories.
If you're referring to something else, please leave a comment on this thread. Thanks.