In economic terms, capital is a means to create wealth, for example farm machinery or a kiln. The capitalist doctrine is that capital should be owned privately and other people can only get to use that capital as the owner sees fit; i.e. by employing workers to operate it. The communist perspective is that all capital is owned by the state, with the capital used by workers as the need arises.
Whichever way you look at it, capital must exist. Without capital, there can be no creation of wealth; wealth being stuff like food, homes, electricity, etc.
From the anarchist perspective, capital is not really 'owned'. Ownership demands legal protection. The anarchist is not subject to rules (i.e. laws) unless he consents to them.
There are methods that a group of anarchists could use to equitably divide capital amongst themselves, and to cooperate in order to use that capital effectively. Anarchists are not averse to following rules, as long as they may elect to follow them or not as they see fit; there must be some benefit to following the rules, or some degree of penalty for not following them (e.g. have to deal with other anarchists shooing you away from access to the capital.) Effectively, when a group of anarchists labours to produce some capital, they then decide together how that capital is to be used and take it upon themselves to protect that capital. The task of protecting it may be farmed out to some other anarchists (like an anarchist police group).
Well I could go into anarchism in depth, but the point is that anarchists don't like to do anything that they don't choose. People want the opportunity to work towards things they want. Capitalism and communism may force people to work towards goals they manifestly don't want, out of personal economic necessity.
I, for example, have certain pie-in-the-sky goals, and until I find people who want to cooperate with me to achieve them, I have to work towards them on my own. That means I have keep working, wasting my time doing things I don't want to do, to pay off my mortgage and my bills and so on. My pie-in-the-sky goals (my project, as I like to call it) will require capital. So, I need to try to make myself self-sufficient, as part of the requisite capital for my project. This would be easier with other people, but until I find others, I need to take positive individual action to make it happen.