Upon purchasing the Tado plugin, you will receive an email containing links to assign your plugins to your switches. Ensure you check your junk as they can turn up there.
For each plugin instance, simply follow the link in the email. You will then need to enter your each device's serial number and authorisation code, both of which can be found in the System > About menu.
Double check the switch and licence you are assigning to it as this step cannot be undone.
Once you have successfully assigned a licence, reboot the switch by pressing the button on the bottom edge.
Once the switch has rebooted, go to Integrations > Add > Tado and enter your Tado account details.
If it successfully connects, you will be prompted to be taken to the climate screen configuration with Go There. You can use this shortcut or navigate there yourself.
From this screen (Screens > Climate) you simply select the zone that you want to control via the Tado integration.
That's it. Now you can navigate back to the Scenes screen and then use the new Climate tab on the left to navigate to the Climate screen.