Follow the steps below:
1 - Start the Thermostat App and select "Account ==> THIRD-PARTY ACCESS" from the main menu
2- Click on the green arrow to access the next screen
3- Enter the credentials of your Legrand account
4- Click "Sign in" to authorize the account linked to the device to the management of third parties
5- Click on the green check to finish the procedure
Now your Smarther thermostats and your Legrand account are enabled to be controlled by third parties (Ie: voice assistants "Google Home" and / or "Amazon Alexa")