The presentation/TV-Out Mode (including laser pointer) is currently not supported in GoodNotes 5 and will be added back.
The new version has been completely rewritten from scratch, to support a better code architecture. That's why some GoodNotes 4 features aren't supported out of the box.
In the meantime, you can continue using GoodNotes 4 if you rely on it in your workflow. We're sorry for the inconvenience. Please keep an eye on the App Store as we're frequently releasing new updates to GoodNotes 5.
Other unimplemented features that will be added back can be found in this article: