@TIG
Yes, very strange.
In the .../Rubyzip/zip folder, I have everything except rbconfig.
I checked for ...zlib.rbs and ...zlib.so and both were present.
I set and/or verified that permissions were all set to 'Full Control' on the folders you mentioned.
Restarted and getting same result.
@TIG
Thanks for the reply. I did the repair but no change.
Also did the Ruby Console lookup you suggested and got "=>nil" both times.
I installed SketchUcationTool.rbz by downloading from here: https://sketchucation.com/resources/plugin-store-download. Then went to the Extension Manager in SU and hit Install, found the file, etc.
The install looks like it works fine. The toolbar shows up, and I can open the Store, the Plugins Mgr. and the Extensions Mgr. But when I try to install an extension from the Store, the install icon just spins. And then when I restart SU, I get the failed to load error message.
Happy to hear any other ideas you have, although this is likely unique to me. And either way, this is not a huge deal as I can simply download/install extensions individually. I just really like the convenience of the Tools extension.
Hi - I had a problem with the extension as well. Downloaded the file, saved to 
drive, and installed it - that seemed to work well. Restarted SU and got an error saying that it failed to load. Error file is below. Lemme know if you want any other info. Also highly likely I'm doing something wrong...
Extension Errors Report
SketchUp: 24.0.484
OS: Windows 11
Ruby: 3.2.2
Extension: SketchUcation (4.4.0)
Error: LoadError (127: The specified procedure could not be found. - C:/Program Files/SketchUp/SketchUp 2024/Tools/RubyStdLib/platform_specific/zlib.so)
<internal:C:/Program Files/SketchUp/SketchUp 2024/Tools/RubyStdLib/rubygems/core_ext/kernel_require.rb>:85:in require' <internal:C:/Program Files/SketchUp/SketchUp 2024/Tools/RubyStdLib/rubygems/core_ext/kernel_require.rb>:85:in require'
c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf-rbztools.rbe:199:in <module:RBZtool>' c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf-rbztools.rbe:171:in <main>'
c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:67:in eval' c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:67:in require'
c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:67:in block in load_files' c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:65:in each'
c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:65:in load_files' c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:70:in module:SCF'
c:/users/kenar/appdata/roaming/sketchup/sketchup 2024/sketchup/plugins/sketchucation/scf_loader.rbe:13:in <main>' C:/Program Files/SketchUp/SketchUp 2024/Tools/extensions.rb:197:in eval'
C:/Program Files/SketchUp/SketchUp 2024/Tools/extensions.rb:197:in require' C:/Program Files/SketchUp/SketchUp 2024/Tools/extensions.rb:197:in load'
C:/Users/kenar/AppData/Roaming/SketchUp/SketchUp 2024/SketchUp/Plugins/SketchUcation.rb:181:in register_extension' C:/Users/kenar/AppData/Roaming/SketchUp/SketchUp 2024/SketchUp/Plugins/SketchUcation.rb:181:in module:SCF'
C:/Users/kenar/AppData/Roaming/SketchUp/SketchUp 2024/SketchUp/Plugins/SketchUcation.rb:17:in `<top (required)>'