The current Mac version of GoodNotes is removed from sale temporarily because it is not compatible with GoodNotes 5.
We're working on a new version for GoodNotes for Mac, that will be compatible with GoodNotes 5. It will be available soon. If you're interested in beta testing the new Mac app pre-release, please sign up for our waiting list. We'll invite you when we start beta testing it.
We're planning to release a first beta version around mid-February 2019.