Confidently wrong. There are different kinds of anarchism, and yours might be fundamentally oppositional to capitalism. But to deny the existence of anarcho-capitalists is counterproductive, because they exist, and they're a serious threat to be aware of.

The idea is that in an anarchist society, there's no governing body to regulate businesses, and so they get to do whatever they want. It results in a neofeudal corporate oligarchy, a la Curtis Yarvin. You can argue that it's not really anarchistic if it results in oppressive systems. They might argue that it's only anarchy if there's nothing stopping them from oppressing you.

The point is, anarchy is a big umbrella, and just because you might be anarcho-syndicalist or something else doesn't mean that your version of anarchy is the only version of anarchy.

Arguing over what constitutes "the true anarchy" is pointless. Critique anarcho-capitalism to your heart's desire, but to deny that it exists implies that there's nothing to critique.