Sometimes people miss the email in their spam folder, or they may not receive it at all. In such cases, it's best to call IRCC before your oath ceremony or speak with the oath officer, who can resend the information. However, if you miss everything, there’s no need to call IRCC afterward, as by the time they take action, your e-certificate will likely already be available in your account.
Thank you for your message. We checked and found that there was an email which came the morning after the oath with instructions and an invite code for the portal. Just signed up for the portal. However no citizenship certificate there yet. We will wait for 2 to 5 Business days as told there. Thanks again.