Cleaning the air conditioner with cleaning foam

Has anyone cleaned the air conditioning evaporator on an Octavia 4 (2021, 81 kW, 1.0 TSI)?

Last winter I had problems with the heater core, and it has since been replaced. However, I can still occasionally notice a musty smell coming from the evaporator.

So far, I haven't been able to figure out exactly where the evaporator is located or where the cleaning foam should be applied. Is it possible to access it from underneath through the condensate drain and clean it that way?

Does anyone have a clear diagram of the entire HVAC system layout?

Thanks in advance.