Honestly, I dont think there's any easy way to deal with this one. Alot of us dont get along well in groups... I daresay this is one of the defining aspects of our so-called condition. I've been in groups with other autistics before, and.... every single one of them collapsed. It's odd really, since so many people on the spectrum require alot of order and organization, yet can then be so incredibly chaotic in every other aspect without realizing it.
I honestly think the most important part is the structure itself. When I think back to those groups, and other things like groups in school and such where I personally would fail, the biggest problem was an overabundance of, and emphasis on, an arbitrary structure and such. Like, here's this guy in charge, here's this list of rules he sets, do exactly this, do exactly that, even if you dont want to do it, DO IT ANYWAY.... and so on. Alot of traditional group structure is simply incompatible with those on the spectrum. It gets us frustrated and stressed out, and causes us to feel confined. Something like a contract just adds to this stress, and that feeling of being penned in.
Now, I have had one very specific good experience with group work. I did some contracted work for a game developer I know, working as part of their team to create a game. Sounds simple, but I'm not a professional, and in fact, had never been contracted to anyone for anything before. Usually, I'm *terrible* in groups, and I dont react too well to being told what to do. I do my best when I'm allowed to figure stuff out and make decisions.
Well, the guy in charge understood all of this. I'm guessing he already had a couple of people in his life that were on the spectrum, because he knew *exactly* how to deal with all of the problems that I presented (and I made sure to explain every one of them to him, when he made the offer, just to make absolutely sure he wanted to go forward with it). The way the whole thing ended up working was pretty unique. Firstly, there was no forced schedule... I worked on it when I wanted to work on it, simple as that. Secondly though, nobody tried to control me, tell me what to do, or assume they knew my role better than I did. In fact, when the project started and I asked "So what should I do first?" (totally expecting to be given a list of orders, like would happen in most projects) his answer was "Well, what do you think you should do first? Whatever that is, just do that". Rather than try to micromanage everything I do... which is frustrating to someone on the spectrum... he simply trusted me to know my role and know what to do (and indeed, I knew the role I needed to play... it was the whole reason I was offered the contract). There also was nobody trying to control the METHOD with which I created my stuff. They didnt care HOW I got it done... just that it was good, simple as that.
Whole thing ended up working out brilliantly. I tended to work on it in bursts, usually when I had a sudden idea for a bit of content to add to it. Nobody ever questioned the stuff I did or the way I did it. Nor did anyone argue with me on any of it. They'd asked me to help because of my mastery of the type of game that was being made, after all... I already knew what I was doing, and nobody tried to do the whole "boss people around simply so they know you're the boss" kind of thing. Which is what often causes conflicts in the workplace or other groups... someone already knows their bloody job and is good at it, but someone above them tries placing unnecessary structure on them just because they are the boss, or "because that's how it's done". That's a bad thing for those on the spectrum, and my situation worked because that wasnt there. The whole thing ended up really working out wonderfully. I made my own decisions, nobody ever tried to question me (again, they had confidence that I knew what I was doing, and in that specific case was the most knowledgable person there about that specific type of game), and because I could work whenever I want, I tended to work in bursts of extreme efficiency and intensity, as is the usual case when any of us are pursuing a special interest. So, very low hours still meant that I had time to create boatloads of stuff.
So.... yeah, that's my experience with SUCCESSFUL group work. It's worth noting that it's pretty much the ONLY successful group work I've ever been a part of. EVERY single other group, whether it was a work thing or a school thing, tried to bring in too much control, or question my methods, or put in silly, unnecessary restrictions on it. Those are the things that kill it for me, and probably for plenty of others on the spectrum. Unfortunately, alot of people that run groups of any sort seem to have a very hard time grasping it. "My way or the highway" seems to be the usual mentality, and that just aint gonna work.
Which is the big thing to keep in mind when dealing with the idea of a contract. Contracts set alot of restrictions, and that can mean big stress and big problems for someone on the spectrum. You'd have to be very, very careful with the whole thing. A contract that might work for one person, would likely break another person entirely. What with how very badly we tend to react to stuff going wrong.
Honestly I dont envy you for the job you've got ahead of you. Must be like trying to herd cats. But I wish you the best of luck anyway.
There, I'm done with my aimless rambling.