Adhd is accommodating probably more frequently in public schools than almost any other category. Students can qualify for special education services as OHI, for instance, in the state where I teach if the symptoms are severe or complicated by other learning disabilities. My son was served throughout his education that way. Those that don't qualify special ed can be accommodated under 504 provisions which more often where I see it.

In college you have to be your own advocate, they won't look out for you first. If you want accommodations you take them with you, arrange those accommodations through the college and hope the professors will follow through. My son chose to go without accommodations in college for his adhd, and while it was a bit of a learning curve, he is actually quite glad he has to figure out how to manage his disability on his own (in retrospect he feels like he was coddled in school too much previously and in a way they created more problems for him). He knows now what he needs to do to manage his issues with adhd, speech, and severe fine motor problems now without someone else doing it for him and feels in the long run he'll be better off.