for Mac is essentially impossible because Adobe transitioned to a subscription-only model years ago.
If you see a site promising a "free download" for CS6 today, it is likely pirated software and may contain malware. Key Facts about Photoshop CS6 on Mac: Photoshop cs6 permanent free trial? - Adobe Community Download Adobe Photoshop Cs6 Full Version Free Mac
Finding a legitimate, free, full version of Adobe Photoshop CS6 for Mac is essentially impossible because Adobe transitioned