He was describing the mindset of Nicol, so I will not attribute the belief behind the phrase to Hesse himself. Nevertheless, the belief is pervasive. And the belief is patently wrong.
Capitalism is not authoritarian. It is the opposite of authoritarian. Capitalism describes nothing more than a system where people make mutually beneficial voluntary transactions. To wit:
I bake bread. I give some to you for some money. I had more bread than I could eat myself, so I am better off getting money for the bread. I win. You had money and could not eat it, so you are better off with the bread. You win.
There is no authoritarianism involved.
It is the self-described and completely misnamed "anarchist" that wants to use force (i.e. "authority," the root word of "authoritarian"), to stop the baker from making "too much" money. It is the statist, not the anarchist, that wants to determine how much money to forcibly take from the baker so he can pay his "fair share" to the collective. It is the statist, not the anarchist, that wants to use force to appropriate the "ill-gotten wealth" of the rich who "exploited the working poor."
Much to the chagrin of my anarcho-capitalist friends, I believe anarchy is neither desirable nor achievable within the next millennium or so. Nevertheless, if a truly stateless society is achieved, it will be based on the mutually beneficial voluntary transactions of its members, and not some ill-defined notion of "fairness" imposed by force on behalf of the collective by those not party to the voluntary transactions of individuals.