Virtual Key
Fleet Telemetry and certain vehicle commands uses mTLS encryption, which requires you to install the Teslemetry's public key, known as the "virtual key", in each of your vehicles using the Tesla app.
You can install the Teslemetry virtual key by selecting the specific vehicle in the Tesla app, opening the following link on that smartphone, and follow the instructions in the Tesla app:
https://tesla.com/_ak/teslemetry.com
If the Tesla App does not open immediately when you click this link, it has not worked.
Next steps
Accounts with owner permission can install the virtual key remotely, but accounts with driver permissions will have an additional step that requires a physical keycard. The Teslemetry console will show the status of the Virtual Key for each vehicle to the owner.
To learn more about Tesla mTLS, see Command Signing.
Troubleshooting
If you open the link and your smartphone opens the Tesla website rather than app, the process has not worked. Try open the Tesla app, ensure you have your vehicle showing, then return to this website (not the Tesla one), and click the link again.
Known issues
If your have more than one app called "Tesla" on your phone, the process wont work. You must remove the other Tesla app.
Certain browsers like Samsung Internet may not open apps from web links, Chrome on Android is known to work.