no letter of authorization is not needed for closed work permit although you need to take your offer letter or employment proof with you to convince that you will work in Canada ..
i have one question for you did your spouse automatically got an authorisation letter or did you apply for the same ? If you applied how much time did it take ?
I am in the same boat got my CWP and my wife’s OWP this month. I want to travel in Jan to Canada but lawyers told need to apply for authorisation letter. I have applied for it yesterday only.