I think that is about Windows, but read check hosts file for blocked entries https://forums.adobe.com/thread/1912777
If you are trying to install something other than the latest Cloud programs, read below
That MAY be a false error message due to Mac El Capitan and OLD programs
This information is a MUST DO to install old programs on Mac El Capitan
-you may not get the same error message, but these two links will help with old programs
Install CS5 on Mac 10.11 https://forums.adobe.com/thread/2003455 may help (also for other than CS5)
-also a TEMPORARY security change https://forums.adobe.com/thread/2039319
FAQ about Mac 10-11 https://forums.adobe.com/thread/1979303