Before you had to mail the cut PR card pieces to IRCC but looks like you need to send a pic these days of the cut PR card for kids. Only after that citizenship certificate is issued.
They have the $100 premium service where they do the form filling for you. Because of it all such rejection happens. If its too much hassle you can opt for it.
In such cases it's going to your consultant. You can ask them to forward it to you. It's a glitch and once you have your account set up you won't need there help.
Not mandatory but select few do get it. It used to be allowed but now you need to do it in Canada.
https://www.canada.ca/en/immigration-refugees-citizenship/services/canadian-citizenship/become-canadian-citizen/apply/submit-fingerprints.html