Akral Design, this is highly unusual. You're doing everything right but for some unknown reason the installer fails to recognize your Photoshop.
Judging from the words 
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| <class XFW::ArgumentError> The handle 0052B9B0 is not a valid window handle  | 
 I suppose you tried to load the plugin manually. You need to copy the two plugin files – "Filter Forge 5 x64.8bf" and "Filter Forge.config" – and then specify the correct plugin settings:
in the "Filter Forge.config" file navigate to the IndependentUI line and change the value to true. Save the changes and restart Photoshop.