Although using ‘Run as administrator’ to install SketchUp from its exe file is the only way to ensure that everything is working properly regarding permissions etc… The UnZIP error from SketchUcation’s ExtensionStore is almost always an indication that you have something blocking SketchUcation from properly downloading the RBZ, before it installs it.
This means an empty RBZ [which is actually a ZIP file] arrives in the Temp folder and can’t be installed.
The cause is almost always your Firewall settings which either blacklist SketchUcation.com or at least it isn’t whitelisted so your overly strict settings block it.
You [or your IT guy] need to look at your Firewall settings and whitelist the following settings…
The sites with *sketchucation.com*
and the IP addresses 178.63.47.155 and 144.76.69.227
A similar issue was discussed here…