You can sync orders by following the below steps:
1) Click Orders Navigation link on the left hand side
2) Click the More Button and Click Sync Order Range
3) Enter the range of orders you want to sync, you can only sync a range of 100 orders at a time
4) Or you can click the More button and select the sync selected orders.
Note, this option does not sync manual order status.
Note: Store of shopping cart type Amazon in OrderCup does not have order sync feature