Cant install Photoshop CS6

You don't specify Mac or Windows, so notes for both

CS6 and earlier programs HAVE NOT BEEN TESTED AND WILL NOT BE UPDATED for Mac El Capitan or newer operating systems

-which means that you try to use CS6 and earlier at YOUR risk of having problems due to Apple updates

-Apple did not maintain backward compatibility with old programs in El Capitan or newer operating systems

--Adobe has a workaround to Apple's problem of not maintaining backward compatibility

--READ HERE https://forums.adobe.com/thread/2301916 for an Adobe solution to installing old programs, including a link to installing the old Java runtime that is required

--Also read for more information https://forums.adobe.com/thread/2458382

--and https://helpx.adobe.com/x-productkb/global/install-or-run-applications-new.html

Two ideas that MAY work to install and/or run old programs in Windows 10

-RIGHT click the program icon or EXE and select a compatibility mode in the pop up option window

-or Run as Administrator http://forums.adobe.com/thread/969395 to assign FULL Windows permissions may help... this says Encore, but is sometimes required for ALL Adobe programs (this is NOT the same as using an Administrator account) so follow the instructions, substituting the name and location of your specific program for Encore

-also https://helpx.adobe.com/x-productkb/global/create-local-administrator-account-windows.html