If you have an active Adobe Creative Cloud All Apps plan, you may still be able to install Fireworks CS6 by enabling the "Show Older Apps" option in your Creative Cloud Desktop app preferences.
Adobe Fireworks CS6 (v12.0) is a discontinued graphic design tool, and while "Portable" versions are often found on third-party sites, they are not official Adobe products and carry significant risks. Official Status and Availability Discontinued : Adobe officially stopped developing Fireworks in Official Downloads Adobe Fireworks CS6 12.0 Portable Download Gratuito