I tried; but got the same error message - "... damaged and can't be opened. You should eject (or close)..."
This worked for me thanks! I'm on : Mac Pro running OSX 10.10 Yosemite. I guess the upgrade reverted my Gatekeeper settings.
Under System Preferences > Security and Privacy
Set Allow Apps Downloaded From:
App Store and Identified Developers
1 person found this helpful
Solved the problem.
Open 'Terminal Mode', which is in the Users Library. (You have to pres 'Alt' to see the Users Library.) Then type in to 'Terminal':
xattr -c /Users/******/Downloads/InDesign_7_5_LS1.dmg (make sure that is the correct path to the correct installation file you are having problems with.)
I did this twice, because once did nothing (spelling error?).
Anyway, now Adobe InDesign is happily installing.
Happy Days..... ;-)