To my knowledge, they can request some forms again if they think there's a mistake and/or missing information.i got mr on 20 aug and take appointment on 28 aug
Today i got another email from ircc
They are saying my form no IMM 5669 IMM 5562 AND IMM 5406 to up load in my online account
They allso assk for another documents about my job and last three pay slip and gave deadlines for submitting 9 sep 2020
I submit my application paper base and now they says uplod online
I not understand this stap
I believe you would have the option to upload these documents from your cic account going in the page to view the application status and messages (for your PR application). There there would be in an option to "View submitted documents or upload documents" that you can click to go for another page (where you would be able to upload the requested documents).