Open ShipStation.

Go to the "Account" ==> API Settings.

To generate the API key, click on the 'Generate API Key' button.

Select the key expiration options and click on the 'Generate' button.

Here you can see the generated API key & Secret key. Click on the 'Done' button.

Go to the "Shipping" ==> Ship From Locations.

Click on the 'Add New Location' button to add a location.

After that, the 'Add New Ship From Location' wizard will appear. Enter the details and click on the 'Save' button.

Create a service-type product.

Go to the sales "Configuration" ==> Delivery Partner.

Enter your ShipStation API credentials, generate the authentication token, and then click Import From ShipStation to sync data. After filling in all details, click the refresh button to update and validate the connection.

You can view the imported data under the 'ShipStation Carriers'.

You can view the imported data under the 'ShipStation Stores'.

You can view the imported data under the 'ShipStation Carriers Services'.

You can view the imported data under the 'ShipStation Carriers Packages'.

You can view the imported data under the 'ShipStation Warehouse'.

Go to the sales "Configuration" ==> Shipping Methods.

Select the 'Delivery Product'.
Tick the 'For Testing' boolean under the 'ShipStation Configuration' tab and fill in all other required details.

Create a quotation and click on the 'Add Shipping' button.

After that, the 'Add a Shipping Method' wizard will appear. Enter all the details and click on the 'Get Rate' button.

Here you can see the generated cost.
Click on the 'Add' button.

Click on the 'Add Rate' button for the rate you want to add under the 'ShipStation Rates' tab.

Here you can see the added ShipStation rate.
Now confirm the quotation.

In the delivery order form view, click the 'Generate ShipStation Shipping Label' button.

In the log note, it shows that the shipping label was successfully generated, along with a downloadable PDF link.

The PDF view looks like this.