Intuit will send you an email with a link that will take you to an application, allowing you to upload your document to the case. You can also do this through the in-product banner at the top of the page or the critical notice on your Payroll Overview page.
If you have already submitted a document, a confirmation window will appear in QuickBooks Online once the submission is complete, confirming its success.

You may continue to encounter prompts to upload documents for 2-3 business days after completing the upload process. If you have already successfully uploaded your documents, disregard these prompts.
You will receive an email if you have additional documents to confirm verification. Access the resolution center to find further details about the specific requested documents.
Please note that the processing times for new sign-ups to Payments or Payroll take 2–3 business days, while for existing Payments or Payroll customers, it takes 7–10 business days once the information is received. Reminder messages in QuickBooks will clear once verification is completed.
Refer to this article to find out other helpful questions about FINTRAC: Need to know about FINTRAC.
Here's an article that'll guide you in recording customer payments in QuickBooks for future use: Frequently asked questions about bank payment deposits in QuickBooks Online.
Feel free to reach out if you have any questions or need further assistance with other tasks in QuickBooks. We're here to help.