Nobody can tell you anything without exact system info or other technical details.
Did you ever solve your issue? If so, how did you get it fixed?
I too am having difficulties installing and running after effects CS6. I am running MacOS Sierra (and updated to High Sierra hoping it might fix the problem but no...)
I've tried installing AE CS6 through Creative Cloud, but it seems to install version 11.0 and will not open
I then downloaded the update patch "AfterEffectsTrial-11.0.4-mul-AdobeUpdate" but I get an error message (I even tried launching the patch via Right Click "Show Package Contents/MacOS/..." but same error
Lastly, after reading some additional forum suggestions, I tried changing permissions under Library/Application Support/Adobe to read/write for all users including all subfolders, but still no luck.
Any additional suggestions anyone might have would be greatly appreciated. It's important for me to be able to share my projects in CS6. Thank you for your time, effort and energy.