Folder Scripts and Plugins
Plugin DLL files should be placed in the "User Plugins" folder on the disk where DesignBuilder can find it. This article explains how to do that.
https://designbuilder.freshdesk.com/support/solutions/articles/103000183359-how-to-install-designbuilder-plugins
https://designbuilder.freshdesk.com/support/solutions/articles/103000183359-how-to-install-designbuilder-plugins