Which of needs to buy a Plex Pass?

Soe was trying to download a movie from my Plex Server to his iPhone. He got this " Please have the server owner to allow sync for you account"

When I tried it was greyed out. Do we both need a Plex Pass for this to be enabled?

Also does Plex scale down the downloads, because my files on server are huge files, 6-12 gigs each. To bug for iPhone

Thanks