Those who can't get it working, do you have the cloud icon showing up on the My Music tab with a lightning bolt in it? That means iTunes is not able to connect to the service that actually provides all this functionality for sync. It has been this way for me for hours now. Despite the service listed as green on the service status page, it seems like it's down. I can only guess it's horribly overwhelmed, which really sucks because the initial setup of this new feature hosed my library and I have been working to restore it to order and without this service working, no music is available on any of my other devices now.
I thought iTunes Match would be the worst user experience with Apple of all time, but, now I am wrong. That just screwed over a ton of metadata, this entirely blocks my music. And if I can roll it back? I still want Apple Music to work. The proposed functionality is exactly what I've wanted for basically years. So I'm not going to quit now, but, still, it's pretty disappointing that it could be this bad after being so hyped.