After client approval, the Proceed without IO button is available to media plans with a vendor with optional IO configuration. Clicking the button accepts the media plan without sending it for vendor acceptance.
Approvals Side Panel - Proceed without an IO
Approvals Side Panel
Note: You are able to send an IO to a vendor with the Optional Payee configuration. The vendor accepts the IO. Click the Send vendor IOs link instead of the Proceed without an IO button in the Approvals side panel.