Zapiet - Pickup + Delivery doesn't currently have an integration with ShipStation app. If you're using both apps, please note the current limitations:
There is no way of preventing your pickup orders from being sent to ShipStation.
If you are using our Rates feature a line property called the _ZapietId will be appended to one item per order. This property is an integral part of how we generate your stores rates and can not be removed automatically.
If you are having a difficulty with these limitations, please contact ShipStation support team and ask them to work with Zapiet on the integration.