No previous thermostat

Good morning,
I recently moved in an apartment that has a tado thermostat (to configure). Unfortunately as part of the installation, it is required to share which one was the previous thermostat or controller and I have no idea of what it was. I tried to proceed through the steps without including this, but at the moment the app looks like everything works, but the heating system never turns on. Does anybody have experienced something similar?
Best regards