“Adobe InDesign CS6” is not optimized for your Mac and needs to be updated.

[Diorenstein]

Please help! 

[marliton]

Hi. That is a common MacOS message when you open old applications. InDesign CS6 is a very old version, so it's a normal message.

[Kat Gilbert]

I moved to InDesign as this is where you can receive help.

[Monika Gause · Accepted solution]

Which system is that? 10.15?

It doesn't support the old stuff anymore. But that has been made quite clear by Apple as well as Adobe during the last few months. So your choice is to eiter update InDesign or downgrade the system.

[Test Screen Name]

10.14 does put this message. It should explain pretty clearly that it's warning you the file will not work in 10.15.