Installing MuseScore on Mac OS-X 10.4

There is one step missing in the Handbook instructions for Mac installation. In the Installer dialog, when you drag the "MU" icon towards the Application folder, another dialog box may pop up with the message "The MuseScore.app could not be moved because Applications cannot be modified" and with two buttons: AUTHENTICATE and OK. (Nothing here about a password.) I'm told that this situation is common. I learned that OK means "deny installation" and AUTHENTICATE means approve and proceed with installation. After clicking AUTHENTICATE, there may or may not be yet another dialog requesting a password. In my OS-X 10.4 installation, no password request appeared; the AUTHENTICATE click did the entire job. I have not tried installation on other releases of Mac OS-X.