Here's the fix, complete with pictures! I tested this with a half dozen people and it worked every time.

Fix for Extension Update Error 20171102

How to fix the “failed to update” error in the Extension Manager on the “Manage” tab. -------------------- First, try just signing out and back in again. You can do so in the top right corner of the Extension Manager in 2018, and in the top right corner of the main SketchUp window in 2019). ...

Google Docs (docs.google.com)

I'm loving SketchFab, but I want my models to display without edges shown. In the file I uploaded, I turned off the edge view, hid the lines, and even softened the edges, but my online SketchFab model still displays the edges.

Anyone have a solution to that? Thanks.

Katya