Hi Arun,
Request For Information will send back the BRM approval request back to the requestor.
When Requestor receieves the BRM request in his work inobx, he can see that in NOTES section tab he will not be able to add the note. But actually when requestor clicks on SUBMIT then it asks for comments to enter in NOTES section 
In order to enable notifications for this process FORWARD and RETURN notifications should be configured in BRM MSMP stage notification settings.
Also check if there is any authorization issue and as well as share if there is any error screenshot.
Regards,
Madhu.