How to turn on proxy media in 12

So, here i am, the annual editing project, freshly installed Resolve 12, and guess what, i cant turn on the proxy media, why? and how do i turn it on?
In short, if i cant, the Resolve is unusable to me, for obvious reasons...
Hope there is a quick solution to this?

Cheers

Pages 221-222 in the v12 manual: "Creating & Using Proxy Media."

I don't believe proxy is included in the beta. I'm anxiously awaiting that myself.