a google search of the error message returned results for a similar issue in accessing the 3D Warehouse, one of the suggestions was to do a dnsflush and that allowed me to properly install the app.
Accessing the extension warehouse is still super slow and I think that will be a separate topic.
If you can, would you mind trying some uninstalls and reinstalls today? We’ve made some improvements that we hope will improve performance. Let us know if you see any changes.
Yes there is is. This thread and category is about the SketchUp Extension Warehouse. If you use the Window > Extension Warehouse menu item, from within SketchUp, users can install, update, anduninstall extensions.