Try going into "Go" on the Finder menu bar and hold down the "Option" key on your computer keyboard until you see "Library" appear. Go into the hidden Library and then into "Preferences." Here you can delete anything that starts with com.notionmusic.
If you continue to have the issue, try right-clicking the app in the Applications folder and go to "Get Info." Try checking the box to run in 32-bit mode. If it will open in 32-bit mode, then more than likely, you have a plug-in that is causing the crash. See if you can remove your plug-ins from your Macintosh HD/Library/Audio/Plug-ins/VST folder and add them back a few at a time to identify the one that is causing the crash.
Try deleting the app entirely from your Applications folder and re-install. When you re-install, make sure that you drag the app into the Applications folder and that you are not launching it from within the mounted .dmg file.
If the issue persist, you may want to log a support ticket. A Tech Support agent will need to look at your system logs and gather information to assist.
