Click on your error and it will open up the blueprint section where the error is. You have to edit your blueprint. The default blueprint is designed to work with 2 engines. If you want it to work for less or more engines you need to edit it. You can do this edit to make the error go away:
Also is you’re new to Unreal Engine, keep in mind this Flight Sim plugin is not a complete solution. It’s a starting point for developers to make their own.