Yeah, I was also confused about it.i did not submit my PR application yet but My lawer said have to submit with nomination approval letter
but the question is , isn't that Express entry already have the electronic nomination is the profile
Note: we might need to fill some information in EE application which is related to nomination letter
I have filled out my EE application and I only found one question which seems relevant:
Has you received a nomination certificate from a province or territory?
I chose "No" as the answer because I haven't received the certificate, but I could still proceed with this answer, and I was not asked for any document about nomination after that.
But anyway, I think it's better to get the nomination letter before submitting the application, so I'll also wait for the nomination certificate.