Yeah, I couldn't find any information on that part either. So, I just approached the statement by talking about why I want to pursue Public Administration, why I want to study at Queen's and what makes me a good candidate.
https://www.mcgill.ca/maxbellschool/programs/mpp-program-overview/admissions-guide
I didn't apply to Max Bell. Though, most grad applications for public administration (at least for domestic students) is due February 1st. I'll assume then, you should expect to hear back around March