Hi
In order to use Apple Pay, your card must be a supported card from a participating issuer. Whilst CIBC is a participating issuer in Canada, not all of its debit cards may necessarily be supported for use with Apple Pay.
It may be the case, for example, that cards issued in conjunction with a CIBC Advantage for Youth account are not supported.
Apple does not publish a list of supported cards.
To confirm whether or not your card is supported for Apple Pay, contact CIBC:
https://www.cibc.com/en/contact-us.html
More information:
Apple Pay participating banks in Canada and the United States - Apple Support
Set up Apple Pay on your iPhone, iPad, or Apple Watch - Apple Support