I have two at university with ASDs and other issues.
When looking at accommodation the main aim has been to reduce stress as much as possible as there will be other stresses you and they have no control over.
I think an ensuite is essential as sharing a bathroom is stressful for most people.
Catering/ self- catering is more difficult and depends on the individual. It they like cooking and are competent then self-catering is likely to be better as it avoids the problems with catering which 10 green bottles outlined above. Bear in mind though that planning, shopping and cooking for every meal can be overwhelming and is different from cooking the odd meal at home.
There is also the problem of shared kitchens. Unless you are incredibly lucky shared kitchens will be messy.
A studio flat resolves that problem but they are expensive. If you want to go down that route make sure that it is very clear on the DSA assessment that it is necessary for disability reasons and why.
Not all universities have quiet halls or flats but it can be a good option if it is offered. They can however be too quiet if everyone has social communication difficulties. Ds was in quiet flats in halls for two years and I don't think he said more than a brief hello to any of his flatmates.
However that is not necessarily a problem as my two actually got to know people in other ways (course mates, ASD support groups and voluntary work).
Other things to consider is how much cleaning the halls provide and how they are managed.
DD is in halls on a large site with 24 hour security which sees itself as a welfare service. That has proved very useful at times and also makes me feel happier about her being there.
Neither of mine have had smooth paths through university and I continue to worry about them daily. However I have found the support and flexibility available from different parts of their university infinitely better than when they were at school.
(SFE is an exception, mainly because they appear to badly managed.)