The Multizone is available from two heating modules connected in your home and which go up on your customer interface.
To activate the Multizone, simply create a new zone by clicking on "My home" and then going to "My products/zones":
Then, move one of your modules to the desired zone with the help of this article: Multizone: How to Identify and move your module to another area?
Your Multizone is now operational, and you can see and manage your new zone from the "Currently" screen.