CS5.5 is not compatible with Mac Sierra, so you may never get it to work properly
You need to complain to Apple... Adobe did not change CS5.5 to make it stop working... Apple changed their operating system and THAT is why your CS5.5 won't work, not because of anything Adobe did
Now I can hate Apple's guts too.
There must be an aftermarket fix or something...
Thanks for the help
(Personal contact information not allowed in the forums--Moderator)
The fix is the upgrade to a newer InDesign version.
However the message suggests that CS5.5 is installed and may be working at least partly. This message, confusingly enough, simply means that the file was last edited by a newer version of InDesign and now you must use that version or later. Same result.