Volunteers, or citizen scientists, are not compensated for their observations and contributions to a project. Motivations to contribute to projects may be out of scientific curiosity, a desire to donate time (or in some cases computer resources) to the betterment of society through scientific research, educational gain by working on the project, potential professional development, or occasionally prize money (though this is not the case for Zooniverse projects).
Citizen Science Alliance (CSA) functions as the governing body of the Zooniverse collection of projects. Individual Zooniverse projects are proposed by a scientific team from a university or research institute and then selected for hosting on the Zooniverse platform. The scientific research (and thus the scientific team) are usually funded from Federal or non-profit grants awarded for specific scientific research projects. To be hosted on the Zooniverse platform, projects either bootstrap their own development through their preexisting grants or CSA uses independently acquired grants (e.g. from the Alfred P. Sloan Foundation) to create the citizen science platform.
CSA, or Zooniverse, employees are actually employed by the separate partner institutions like the University of Oxford (the original site) and the Adler Planetarium. Grants to fund the administrative support and technical development are obtained through these partner institutions from Federal and non-profit sources, and then Zooniverse “employees” are employed by the research institutions themselves, but devote their time toward Zooniverse initiatives.
Some citizen science organizations may have a more centralized organization and often the technical team (people who create an observation platform, if needed) and scientific team are integrated and work directly with the volunteers. The consortium of scientific collaborators and projects around Zooniverse makes this centralized organization and funding stream more challenging, so the organization has adapted to make a flexible, cloud-like organization model to float funding and personnel resources between partners.
Most of the readings from class addressed issues related to licensing software, using open sourced software, or developing code for open source software. Zooniverse has done what I think is a superb job adapting the citizen science model of research to fit within the pre-existing funding infrastructure of scientific research (i.e. conducting research through Federal or non-profit grants).