My Mac OS X 10.6.8 won't open PHotoshop CS6 trial
You downloaded the photoshop cs6 mac version from here:
http://helpx.adobe.com/x-productkb/policy-pricing/cs6-product-downloads.html
Does your mac have a 64 bit processor?
http://support.apple.com/en-us/HT201948
If you have a 64 bit processor, have you tried unistalling photoshop cs6 and reinstalling?
(Use the Uninstall Adobe Photoshop CS6 in the photoshop cs6 application folder)