Anarchy isn't compatible with socialism since socialism by necessity requires redistribution of goods, often at gunpoint, and often by a body of monopolized force (ie govt). Anarchism only works within a completely free trade structure in which individuals are allowed to create and exchange without coercion from any entity.
Anarchy would allow individuals to join socialist organizations if they chose, but such organizations would be violating the spirit of anarchy if they were to coerce outsiders into joining them.