@scalas
Consider manually removing the SketchUcation subfolder from within the Plugins folder, and also removing the !SketchUcation_loader.rb file.
Please [re]download the latest SketchUcation PluginStore Toolset version from the Resources menu link above, or its PluginStore entry [v2.6.1].
Use the SketchUp native Window > Preferences > Extensions > Install... button to install it.
Restart SketchUp.
Now, with the 'Ruby Console' open, try using the SketchUcation PluginStore dialog from within SketchUp...
If you choose to AutoInstall a Plugin what happens ?
Your error message suggests that the SCF toolset was somehow not correctly installed.
The SCF_dialog RBS's code calls some RBZtool functions - these should have been loaded at the start from another RBS in the ../Plugins/SketchUcation subfolder...
So the error ...undefined methodset_choi' for RBZtool:Module` should NEVER happen, because it does indeed include that method in its code !
This is what the correctly installed subfolder should look like...
Capture.PNG
Report back...