It's not enough to pick "window", you need to either adjust margins / plot offset or have a 'center plot on page" setting too https://knowledge.autodesk.com/support/autocad-for-mac/getting-started/caas/CloudHelp/cloudhelp/2015...
https://knowledge.autodesk.com/support/autocad-for-mac/troubleshooting/caas/sfdcarticles/sfdcarticle...