Guess my idea of a university based AS support group is no longer unique
. In futherance to what davethenat said, you may also want to talk to student services such as counseling, student welfare and services which cater to students with disabilities/disorders. They would probably be willing to give you support in this as having a bunch of students with a particular set of disorders supporting each other would benefit them as well in terms of ensuring those students get better supported with less cost to them in the long term. It would also further justify that department's existence and perhaps result in a bigger funding allocation to them.
I'm actually heavily involved with the student clubs on my campus and that extensive experience and knowledge is telling me to gain support and approval from the relevant student services first before considering a club through my university's clubs department. Firstly because those student services are best placed to advise me on what exactly needs to be done in the everyday running of such a group, they may have the funding or means to support it themselves and they deal with the potential members regularly so they are the best placed to promote it. And it sounds better if the proposal that went to the dean of students desk or clubs department came from the professionals from students services.
I'm a bit sleepy so this may not make much sense.