If the previous owner of your car has not removed their profiles and connected phones, a factory reset of the car is needed. You can do this yourself via the car's centre display or ask the previous owner to do it via the Volvo Cars app.
You can connect the Volvo Cars app to your wallbox, even as a non-Volvo owner. This allows you to access all of the available charging functions for your wallbox.
As the car owner, you'll receive a PIN code from Volvo support to verify authorisation for certain connected services. This does not apply to cars with Google built-in.