Re: Unable to start: The Sims 4 is already running - Mac only
@CharKonink
Sounds like you haven't granted all permissions to the external drive and/or Documents folder for the game to access your user data in the original account. You can check this in System Preferences > Security & Privacy > Files and Folders and make sure The Sims 4 has access to removable volumes and your Documents folder.
If you want to carry on playing in the new user account just copy your saves over from the saves folder in your old user account to the saves folder in the new user account.
Sounds like you haven't granted all permissions to the external drive and/or Documents folder for the game to access your user data in the original account. You can check this in System Preferences > Security & Privacy > Files and Folders and make sure The Sims 4 has access to removable volumes and your Documents folder.
If you want to carry on playing in the new user account just copy your saves over from the saves folder in your old user account to the saves folder in the new user account.