The spec sheet calls for less than 1 kWh per day. Let's assume it is 1 kWh per day. 1 kWh in a 12V battery is 85Ah. So one day without sun equals 85Ah gone from the battery (you fill in the number of bad weather days here). I strongly suggest using a lifepo4 battery of you plan to use this for months/years. Using the cars battery is possible, but once the car battery is discharged you can no longer start it. Using a second lead acid battery is possible, but those cannot be discharged too much. So the 85Ah per day transmorph into at least 160Ah per day. And lead acid has a limited number of cycles.

Conclusion : 1 12V lifepo4 battery with number-of-bad-days X 85Ah. Call again if it is a short term thing for a few days per year.

1 kWh per day from a solar panel equals roughly 200W panel, assuming full sun for 8h and a perfect orientation. The car has a flat roof, so it's not perfect orientation. The panel is the cheap part and you will not have perfect sun all the time. And parking the car in full sun will drive up the power needed by the fridge. I would look for 2 200W panels, whatever fits the roof. I would use rigids unless the car is old. I would glue flexible panels onto old beater cars. Those panels have a limited lifetime, but save the hassle of setting up something rigid and flat on something curved.

Battery and panels: https://www.renogy.com/

You need to feed the energy from the panels into the battery. Those things are called solar chargers. You can get very cheap ones ( https://www.amazon.com/WERCHTAY-Controller-Intelligent-Regulator-Adjustable/dp/B09LLMK7PD ) with a life expectancy of a few years or much more expensive one with mostly indefinite life ( https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-75-10-75-15-100-15-100-20 ). For details ask again after you have picked panels fitting the shape of the roof. Renogy also has those chargers.

About the fan: it's a rounding error compared the fridge. Get a 12V PC fans and connect them via a battery monitor to the battery. The consumption doesn't really matter. The fans typically run below 10Ah per day.

You can throw a DC-DC charger into the mix. Those will charge the fridge battery while the engine is running. Useful if you plan to move around, useless if the car is parked all day, all week.