I'm assuming you're on a Windows machine? This should fix your issue:
1) Download the Adobe Creative Clouder Cleaner Tool from here
2) Remove Fireworks by running the cleaner tool (run as administrator) => select language => agree to terms type'Y' => select 1. All => 2. Adobe Fireworks CS6
3) Go to C:\Program Files (x86)\Common Files\Adobe\OOBE\ and rename or delete the folder 'PDApp'
4) Go to C:\Users\username\AppData\Roaming\Adobe\ and rename or delete the folder 'CS6ServiceManager'
5) Now open the Creative Cloud app and turn off automatic updates; click your profile icon (top right) => Preferences => Apps => make sure Auto-update is off (if you leave Auto-update on, Fireworks will be updated and you'll most likely end up with the same issue again).
6) Reboot your system for good measure
7) Download this offline Fireworks installer that I saved , unzip it and install Fireworks **NOTE** Choose 'TRY' when presented with options, you may additionally be asked to sign in with your Adobe credentials
😎 When you launch Fireworks for the first time, you may be prompted to sign in with your Adobe credentials, if you then see a button 'license this software' click it, and you should be good to go.