Hi @DavidBrown,
Are you a teacher, assistant, or Canvas admin? Things like this will vary at different schools/institutions, but since you mentioned connecting to an SIS, I'll say as a Canvas Admin that access to a system like that will almost always have to go through an IT department and there will usually be data security assessments and agreements that would likely be needed if your school even allows 3rd parties to access the SIS at all. I know it seems like a simple request to let a system talk to your SIS, but in reality it's a very complex issue and one that will probably take a while to work through. Your local IT Team (assuming that's not you) would probably be the best place to start for a request like this.
Hope this helps!
-Chris
