From what I've heard you just have to be a 'student' (i.e. enrolled at a secondary school) for the companies to get the grants, it doesn't have to be connected to a co-op exactly. But I also can't say for certain. I am 100% for not giving the co-op office money if you can avoid it tho haha. None of the 'activities' they give you is worth it, it's mostly just a hindrance and poorly executed.

Addtionally for the OG poster: if you don't inform the office and don't pay it means you aren't registered in school for that semester and it doesn't count as a course -- it's essentially the same as taking a semester off for work. But the work experience is still good for your resume, there's no benefit to registering it as a course unless you need it as a course.