When a buyer clicks to Accept/Reject an invoice, they will be presented with a checkbox that allows them to select if they have received the items (This checkbox is only visible when receiving has not yet been completed.). By ticking the box and selecting Accept, the goods will be received along with the acceptance of the invoice.
When the invoice falls outside the configured tolerances set by your community and fails matching, it will go into the Pending Order Acceptance state and the buyer will receive a notification to let them know it is sitting with them to approve or decline the invoice.
The buyer can access this invoice via their Tasks menu and once they press Accept/Reject, they will have the option to receive the items along with accepting the invoice.
Based on your communities setup, the invoice then gets routed for delegated approval. For more information on the process, see Accepting Invoices.