It is unfathamable that I bought and own Fireworks Mac version, and that logging in with my adobe ID I cannot download it from my account. I called adobe, after being passed to 4 people I was told its unsupported, and I have to message an obscure forum board, and that somehow miraculously someone will write me back with a link to download the program I already own. It is a wonder this company even survives with this kind of obscure customer service and protocols. And its a wonder in this terrible service and huge expense for your software there aren't companies who have competed and won over your business. What a shame. If there was an alternative I knew of, with this experience I would never buy an adobe product ever again. The company saves the money of no longer sending out CD's of the programs we purchase, and now leaves me after 30 min of being passed to people in India who don't speak English well enough- that this is the path for me to obtain my program download.
The Fireworks CS4 trial can be downloaded via here:
Follow the instructions to the letter - otherwise you will be unable to download the installer. After installing, use your serial key to activate it.
If required, the FW CS4 updates you can find here:
As you are probably aware of, Fireworks is no longer developed or supported by Adobe - both ended back in May 2013.
By the way, the latest version of MacOsX (El Capitan) does not work that well with Fireworks CS6 - to run it, you will need to install an older, insecure, version of Java - something which is advised against.
Fireworks is dead, and Photoshop is not a great replacement - although Adobe touts it as one. Since you work on a Mac, perhaps consider Affinity Designer, or Sketch. I use Photoline myself. Full licenses, no subscriptions. However, none of these applications offer the exact same feature set as Fireworks.