Access the Theme Category, not a Page or Post Category

We are using the "Enfold" theme to display a portfolio of items and need to create navigation within categories that is both easy to create and to maintain.

If we could access the category name, id, or slug value, we could use a plugin to add specific navigation widgets to a side menu, which would be ideal. However, how to access the theme category is not apparent.

Any suggestions for how to access the theme category values or to use another way of creating navigation based on a theme category/subcategory?

Thanks in advance.