Where did you find the bottom docs so we can get it updated? I see:
auto_complete_duration string
The duration of time after which an open and accepted pickup fulfillment will automatically move to the COMPLETED state. Must be in RFC3339 duration format e.g., "P1W3D".
If not set, this pickup fulfillment will remain accepted until it is canceled or completed.
So the duration starts after the pickup has been accepted.