There are two fundamental problems with anarchocapitalism
private law, private violence companies, private judges and individuals forcing their values and beliefs on others through purchasing these is not anarchist, it is merely private statism. Anarchism merely states opposition to all external authority, conflict resolution, and economic models are not defined. NAP is nice and all but its a human protocol not a part of anarchism. that said i like the NAP although there are multiple forms of agression not just violence altough its the worst.
Land cannot be owned only possessed
land can be used, and built upon, but being 3d land mammals we require a 3d just to exist. Using violence to hoard land you do not use prevents others from freely using to cover their needs and forms a monopoly over the land, causing the renters to be economic slaves to the landlords. This requires a more indepth analysis but i would be happy to provide it.
That said capital (goods that create goods) can be privately owned. Land is a complex thing that cannot be allowed to be monopolized. Besides who determines that? no one. Anarchism requires a lot of common sense to work, not a fixed code like the NAP or others.
It's a principle, nothing else The things people call it, or the things they derive from it is a second thing. But it's not to say that that is the thing that will be the case.
For instance a private DEFENSE company may be something that follows but it's not a given. It could just as well be a neighbourhood watch or a defense organization with volunteers, or maybe someone says; I defend myself.
Or I defend my family.
Again it's a principle not a system,not a fixed code, not a human protocol, I've seen some people think of it like a constitution, or someone who wants to make a contract and let everybody sign it. Some think it's a law that needs to be implemented. It's a principle nothing else.
I would say that there is more...
I think that the incentive would be to not own so much property that you could not afford to manage it. The larger the property owned the harder/more expensive it would be to keep it from those who would squat on/ take over it. It seems to me that the less you own in an an-cap society the better off you are. I could be wrong. This is all off the cuff.