The quest doesnt seem to exist anymore?
But anyway the farm got cows you can milk. You don't need anything, just "use" the cow and start milking

Milking is easy! There's no time-pressure so take it calm. Just hold down 1 button each time, not to far down or you will hurt the cow and fail and you have to start over again loosing that session's energy points.
Hold down left button to around middle and... *release*
And then press right button to around middle and... *release" and you just do that until the can is filled.
You got like 30 sec to do it and thats more than enough time!

Each milking-session cost 5 energy-points and gives you around 5-10 milk!

And each cow got a cooldown on around 1-2 minutes before you can milk it again!