The extension system is accessible from the menu of the left column in a home.
When you are in the home, click on the "Information" button in the left column and then click on the "EXTENSIONS" tab on the page.
> INFORMATION> EXTENSIONS
Extensions are linked to the user's profile and home. There is no way to activate an extension for all the homes in which you are associated. The reason is that it is often necessary to configure an extension specifically for a home.
The extensions are being tested. They are temporarily disabled but will be available soon.