If it shows your biometrics enrollment date, that's it, you don't need to do anything, it's been completed.
I did not see the language you referred to about uploading in your biometrics letter - I suspect it referred to something else.
If you're really paranoid you could upload via webform your biometrics receipt or chit, but again - if enrolled, it's done.
Thank you! That's all I needed to know. Hopefully the DM status in ECAS results in a happy letter from IRCC in due course.