ShipWorks is a very feature-rich platform. It is hard to imagine any printer would not be compatible with ShipWorks. Because of its wide support, a few one-time steps are required to complete the setup.
Firstly, please watch this tutorial video by ShipWorks.
You will then need to tweak a few settings to have the label in the correct orientation.
1) Change the label and sheet dimensions to 4 x 6
2) Download Rollo Template for ShipWorks and copy its content
3) Delete the existing content in "Code" tab and paste the code from step 2 in its place.
4) Preview the label to ensure it looks correct using the "Preview" tab