Hi! AWS Developer Advocate here. Depending on the nonprofit/charity status it's possible they could qualify for free or reduced price hosting. There are a few different programs that you could qualify for.

There is also the Techsoup organization, which helps nonprofits and charities with technology needs: https://page.techsoup.org/amazon-web-services-for-nonprofits

I would highly recommend looking through there for not just AWS specific tools & services, but a wide variety of solutions that might help this charity.

Please feel free to reach out directly to me for additional assistance. Hope this helps!