Wix does not mention information about nonprofit discounts on the site, but you can always contact its support to clarify. It has a free plan for everyone, but it is very limited in terms of features. For example, you cannot accept donations, have a custom domain, and your site will contain Wix ads.  However, they have good educational resources teaching how to build and maintain a nonprofit website, as well as several nonprofit website templates. You may consider upgrading to the paid plan.