My point was only that I can't tell you why it isn't properly logging in if you don't show the part where it is trying to log in.
If you entered your username and password info where indicated in the commands that James posted above, the command group should work as follows:
1. When you first launch VC, the 1st command is automatically triggered. It is just invisibly setting up the Tado RoboBrowser, in preparation for you to issue your thermostat command.
2. When you issue the "Turn thermostat to auto/off/manual mode" voice command, the command checks to see whether you still need to log in or whether you're already logged in (by checking whether the Tado Robobrowser is stuck on the sign-in page or whether it is able to navigate properly to the control panel page).
If you are not yet logged in, it should automatically log in for you, by triggering the "sign-in to Tado" command. Once it has signed in, it will automatically navigate to the control panel page and complete your request. If you are already signed in, it will immediately complete your request.
So, by not giving us your full log (as the wiki instructions indicate that users should do) you prevent us from seeing whether it properly recognizes that you are not signed in and attempts to sign in. All we can see is the last part of the command failing. The last part of the command is always going to fail if it's not logging in properly -- or there could be some other reason. Without being able to see the complete execution of the entire script, there is no way for us to deduce the problem.
... Yes, the log will have your login info in it if you have entered those into the VC command where indicated. It will show your email address and the password you use. That information you can redact, but as you're still learning how VC works and don't seem to quite understand the command structure yet, it is better for you to let us decide what log information is relevant and what isn't.
If you're concerned about the length of the log, you can restart VC and then immediately execute the Tado commands and then close VC right away. That way the log should be a reasonable length.