If your debit card is simply replacing an expiring debit card then your PIN is the same. If you have a new debit card number OR if last debit card was lost/stolen then you will receive a PIN via mail. New PINs are typically received 1-2 days after the debit card. For security purposes they are mailed at separate times.
If you did not receive it, please contact the Credit Union at 800-914-8619 and a Member Service Representative will be able to help you.