Turn on the air fryer and then set the time and temperature, based on the recommended temperature and cooking time on the packet of hash browns.
I always start with ½ of the recommended packet cooking time, shaking the basket once during the cooking time, or flipping the hash browns over if I'm not feeling lazy, and then I will also set the temperature to 20C - 30C lower than the packet recommends while cooking.
Halfway through that cooking time I will give the basket a good shake, or turn over the hash browns with tongs. I always wear oven gloves when doing this, as I've accidentally burned myself a few times on the Ninja Foodi basket now.
If the hash browns are beginning to brown then after the halfway mark I'd just add a couple of minutes to the cooking time and then check back every 2 minutes or so, as they will turn brown very fast once they are cooked and you don't want to burn them.
I find that 10 minutes at 180C (355F approx) is usually the right amount of cooking time for most frozen hash browns. This is similar to cooking other foods, such as air fryer frozen chicken nuggets, which is great if I want to make a fast but simple tea for my girls before they go to bed.