check the Google Drive in your account 

 

 

click on " Authorize With Google Docs "

will sign with Solvay account

 

Done

 

According to Confluence support page, Google Drive plugin is experiencing an unpleasant redirection after you click on the "Authorize with Google Doc" to show another page with "This app isn't verified".
You can follow the steps below to bypass this page.

  1. Click on the "Advanced" to expand more option.
  2. Click on "Go to solvay.com (unsafe).
  3. Click on Allow.
  4. You should see the success message as in the step "Done" above.