RPRF receipt not required in this case. VFS AWB email says not to include unnecessary documents - "
Do not send any additional document in your package like Biometric Instruction letter, Copy of Payment receipt etc."
IRCC PPR letter clearly says to include this receipt if the fee is paid now. "If not yet paid, Right of Permanent Residence Fee (RPRF) for you and your accompanying spouse (if applicable). We strongly encourage you to pay your fees online and provide a copy of the receipt. To pay your fees online, click here:
https://eservices.cic.gc.ca/epay/welcome.do. "