After tapping into passenger rear door speaker to supply audio to new subwoofer, no audio comes from any speakers and none of the volume controls will work. Both the knob on the stereo and the volume on the steering wheel no longer control the volume on the head unit. No audio is going to any speakers not even the usual beeps.
It would seem that "professional" is the wrong adjective to describe your installation. The factory amplifier in 2024 models provides separate output specifically for a subwoofer. Please take your car to an actual professional.
No. Apparently you have to have converters due to the smart current monitor going to the speakers. Even if you tie into the factory amp. The shop estimated around $1200