On Mac OSX Catalina, I get the “mac.xpl cannot be loaded because the developer cannot be verified” error

For users on Catalina, they will need to manually approve the XPL. Please follow the instructions stated here: https://forums.x-plane.org/index.php?/forums/topic/193236-macxpl-cannot-be-loaded-because-the-developer-cannot-be-verified/&do=findComment&comment=1774578 If still the plugin is not loaded, follow the instructions shown in this post: https://forums.x-plane.org/index.php?/forums/topic/194055-mac-os-x-catalina-and-macxpl-files/&do=findComment&comment=1935328 You can find more general information