Hi brett-sydneychef!
Welcome to the QuickBooks Community, and thank you for your first post.
An issue number is not usually required when connecting accounts to QuickBooks Online. I suggest contacting your bank to know what your issue number is. I tried Googling it and found that it's the first 6-digit number on a debit card, which identifies the card issuer. However, it may not be the case for your account, so it's better to contact your bank.
You can also check about categorising and reconciling transactions for your reference in the future.
I'm just a comment away should you need more details about connecting an account. Take care and have a good one!
