If you can't find the impact areas of your organization when completing your profile, you can choose the option "Other":
Make sure you fill in in detail the "About Us" and "How we're making an impact" sections of your profile to properly showcase how you are causing a positive impact in the world.
This will not only comprehensively demonstrate your work and positive impact but will also attract the right talent to apply for your jobs - the independent contractors who support and are passionate about the same causes and will be the perfect fit for your projects.
To learn more about how to hire the perfect talent, check this article.