Even though your son didn't work, he would have to file a tax return to claim his tuition and also to transfer it to you.
This FAQ tells you how to transfer unused tuition credits: https://turbotax.community.intuit.ca/community/family-education/help/how-do-i-transfer-my-unused-tuition-credits-to-someone-else/00/873652
This FAQ tells you how to enter tuition transferred from a spouse/partner or a child: https://turbotax.community.intuit.ca/community/family-education/help/how-do-i-enter-tuition-transferred-from-my-spouse-partner-or-my-child/00/873447