You can read these steps or watch them in this video to login using this website.
Install an app to get your Tesla tokens
Android: you can use the Wear for Tesla app to login or get your tokens.
iPhone: you can use this app to get your tokens.
Enter the values
After getting your Tokens, paste each corresponding value on each field.
Click on create session
You will get a Secret Code that you will need to enter on your smartwatch.