A FireFox addon for Extended Bosch thermostat ha-pro (CT200 cloud) integrations in HomeAssistant. This addon will help you extract the needed key for your installation.
This is the HA Integration: https://github.com/CaseyRo/ha_bosch
Also works for: https://github.com/serbanb11/bosch-homecom-hass
Follow the instructions in HA. It tells you to login to your SingleKey ID. After login it will not redirect the site, a "Continue" will pop-up. Press on that and then check on this addon, you will now have the needed key to continue your setup/re-login.
Good luck! :)