The project owner is responsible for paying providers they have invited to the team.
When a person accepts an invitation to a project, they provide a bid for rate, min & max hours, time available, etc... If this bid is accepted, the next step is to establish the first milestone with the project owner or delegate. When the milestone is agreed to, the project owner places funds in the escrow account in the amount of the estimate for the first milestone. At that point, the provider is alerted that the funds are available in escrow and they should begin work.
Once the milestone is reached, the provider marks the milestone as complete and the project owner (and project manager delegates) are alerted. The milestone is accepted, and payment is automatically made to the provider based on their payment preferences. By default, payment is made via PayPal. Providers can choose to receive a check in the mail or direct deposit as well.