After some further investigation it appears that this is happening due to “third party cookies” getting blocked. In our domain we globally disallow third-party cookies. For some reason the cookies that are created from the Google authentication are considered “third party” and therefor getting blocked. This results in the Sketchup website believing that you failed to sign in and presents the “Sign In Error”.
In the original photo of the error you can see that the browser is blocking cookies by the small icon that appears on the right side of the address bar.
I have found that adding “accounts.google.com” to the “Allow Cookies for URL Patterns” in the GAFE admin console seems to resolve this issue. The white list seems to supersede the “third party” flag and allows these cookies to be passed correctly to the Sketchup website.
If your domain has the “Allow user to decide whether to allow third-party cookies” option set I would check the cookie preferences for the users who are getting this error. I would assume adding the entry to the white list would also fix this issue but I have not tested it.
I’m still not sure why these cookies are getting flagged as “third party” but hopefully the Sketchup team can resolve this issue so we don’t have to add a white list entry to use their app.