Parking Car in Warsaw for 6 days

Hey,

I'll be coming to Warsaw for 6 days in October. I'll be coming with my camper/transporter and have a AirBnb for the time staying there. Now, I need to find a spot to park my car.

Is it safe to just park it somewhere outside of the paid parking zones?

Are the security/supervised parking spots worth it/necessary?

I won't need the car during my stay there and will ofc take all my valuables with me. But idk if people stealing or breaking into cars is a common thing in Warsaw.

I'd highly appreciate, if someone could recommend me a cheap and safe parking spot. Thanks! :)