Upper Canada College is the most elite private school in the country so chances are they won't welcoming anyone using the track.
Yikes. Their gates were open, they had social distancing signs up, and there were a few dozen civs lounging on their lawns, so it seems they are at least a little welcoming during the summer. I tossed a frisbee on one of their soccer fields for a bit without a problem.
I could be totally wrong, hopefully. I trust wouldn't be the same in the US equivilant?