Power consumption high = low battery output or voltage/potential failing battery
Engine must be running = if diesel, not up to temperature or DPF regen in progress
Drivers seat belt not fastened = one of the pre-requisites of the start stop system is that the drivers door is closed and seat belt fastened
I had endless issues with the power consumption message appearing until the battery was replaced (2.0 diesel), and message about engine must be running appears every time a regen starts (as seen and monitored by the VAG DPF app)
Give the battery a charge (make sure you use a charger suitable for EFB/AGM batteries) and if diesel invest in a carista module and VAG DPF app on your phone to keep an eye on when regens are active. Screenshot of the DPF app attached