Help! Apogee Electronics might want to make their software accessible; they want to know more!

I figure I'll weigh in as well: in my experience being part of a digital accessibility team that clawed its way from the back offices of a large enterprise to the forefront of said organization's digital development efforts, all the documentation in the world isn't going to help explain the "why" of making an app accessible: you also need to explain disability, and that it could happen to anyone. Microsoft's inclusive design toolkit has some great infographics that explain that disability can be perminant, temporary or situational, and that something like 15% of the world's population has a disability. That's the biggest untapped market segment the corporate world has had access to since the 1940s onward when women began joining the workplace. You could also leverage videos such as Apple's "sady" video, unveiled for 2016's global accessibility awareness day. Give them documentation, but also convince them that the learning and implementation will return ten fold from a business perspective.