We installed the app https://www.ecwid.com/apps/storemanagement/shipstation and followed the installation process.

We need to be logged into the both ecwid and shipstation to complete the setup.

Once setup is completed, You can try importing the existing orders from ecwid into shipstation if needed. The import failed when we tried.

The issue was resolved by ensuring that each product had proper weight and dimensions added in Ecwid. 

ShipStation requires this information to calculate shipping rates and import orders correctly

Additionally, the product must be marked as a physical item with shipping enabled. Without these settings, orders may appear normal in Ecwid but will fail to sync with ShipStation. After updating these fields, the orders began importing without any problems.

For more details please visit https://support.ecwid.com/hc/en-us/articles/360015229920-Sending-orders-to-ShipStation