If you're not a Canadian citizen or Permanent Resident of Canada, you must have a valid study permit to study in Canada at the University of Waterloo unless you meet one of the exemptions

Normally, one exemption is when the duration of your program of study is six months or less. However, due to the current travel restrictions during the COVID-19 pandemic, to enter Canada all international students need to have either a valid study permit or a letter of introduction (study permit approval letter issued outside of Canada). Please read about the requirements to enter Canada as an international student on our "How should I prepare?" FAQ webpage

If you attended high school in Canada, we recommend that you apply for your post-secondary study permit as soon as possible after you are accepted to the University of Waterloo, so that you have the ability to work part-time during your full-time studies. If your high school study permit has any conditions or remarks only allowing study at the high school level or at a specific high school, you need to receive your post-secondary study permit before your first day of classes at the University.