But I'm just not really sure what the disabilities office has to offer students who make a lot of errors. Does anyone know?
Depends.
Some places offer private or very small group tutoring for disability management. I know that we have eleventy-bazillion opportunities for people who need help with organization, with organizing thoughts, and with processing difficulties.
However, some places may not have any of those programs. What the student needs then is to find someone who tutors how to deal with dyslexia. I don't know what that would be since I'm not an expert in the field, but I know that restructuring how to approach writing, keeping track of common errors to triple check, and such is part of the process.
Vox is absolutely right, though, that what the students don't need is copy editors instead of the kind of directed teaching on how to catch one's own errors while practicing techniques that result in fewer errors.