There is a compatibility issue with KeyAccess (Sassafrass' KeyServer client software) and macOS Catalina, and later, that will cause Finale to hang during launch. This can happen even when Finale is not using KeyAccess or KeyServer for authorization and the user may not be aware that this software is even installed.
Finale will start to launch and appear in the user's Dock but stop at that point. The Finale window or menu will not show either but it will be available in the Force Quit menu (Apple menu > Force Quit).
KeyAccess is used as a third-party authentication tool for Finale and other software. This is primarily used on machines administered by someone other than the main user, or in computer lab environments.
You can check if you have this software by going to the Apple menu and selecting About this Mac and then System Report. Click Applications under Software, check if KeyAccess is listed here and check the version number. This needs to be version 220.127.116.11 (or later) to work correctly on macOS Catalina or later.
If need be, you can update to the latest version at the link below or by contacting your computer's administrator.