Well you are in the right place.
What you need is root and file explorer. I personally use x-plore and fx.
Just head-on to "/data/fota/". There will be a file called update.zip. Just copy it wherever you want.
I think this will work in all latest Samsung mobiles.
[IF YOU ARE GONNA COPY THIS AND POST ANYWHERE, PLEASE LINK IT TO THIS THREAD]
An optional thanx will be appreciated!
Sent from my SM-G7102