go here:
https://www.canada.ca/en/employment-social-development/services/sin/before-applying.html
Temporary residents must provide an original of one of the following:
Work permit issued by Immigration, Refugees and Citizenship Canada (IRCC).
Study permit issued by IRCC, indicating that you are authorized to work in Canada:
a study permit that indicates the permit holder “may accept employment” or “may work” in Canada; or
a study permit and a “confirmation to work off campus” letter issued by IRCC prior to February 11, 2015.
If neither of these requirements is met, you must contact IRCC to verify if you are eligible to apply for an amended study permit.