If the workers are motivated, they can self-organize. However, a hierachy in a production facility or across multiple is not incompatible with anarchy on a national scale. There can be different kind of jobs. There can be someone who just organizes logistics, replacing the manager.
All of this has nothing to do with political systems like anarchism or oligarchy tho. People like to mix them up, but these are economic systems; in this case even microeconomic.