Why we removed support for an old iPadOS / macOS version
Maintaining support for older iPadOS versions would limit our ability to ensure a reliable, high-performance experience for our users, as we wouldn't be able to fully utilize the latest technologies offered by the latest iPadOS / macOS versions.
How to update your system software
iPadOS: Open the Settings app, tap General > Software Update and see if you can bring your device software up to date to iPadOS 15.4 or later. macOS: Open System Preferences > Software Update and see if you can bring your system up to macOS Monterey 12.3 or later.
If your system software can't be updated, we highly recommend upgrading your device/machine to ensure you can get all future updates of the app.
If you choose to stay on an older iPadOS / macOS version
You'll still be able to use your existing GoodNotes 5 installation as usual, but unfortunately will no longer receive future bug fixes and improvements to the app. For example, iCloud Sync and Auto Backup with third-party cloud services may be affected when we introduce new improvements/bug fixes for those features in the future.