It's the new way you sign in to Acrolinx sidebar integrations. Acrolinx Sign-in works whether your server is configured to authorize users with Acrolinx or Enterprise Federated Authentication.
Previously, you entered your username and password directly in the Sidebar. Now, you'll be prompted to click a button which opens a sign-in page in a browser window. After you sign in to Acrolinx to give the application permission to access, you can return to the sidebar and start using Acrolinx. If you update to the 5.2 server, all sidebar integrations will immediately start using the new Acrolinx sign-in feature.
0. Some integrations like those for Google Docs, Google Sheets, Chrome, and Firefox show a server section. In a first step, you enter the Acrolinx server address to connect.
1. The Sidebar shows a SIGN IN button. Click SIGN IN to open the Acrolinx sign-in page in a browser.
2. Enter your user name and password to sign in.
3. Click CONFIRM to allow the specified application to access your Acrolinx account.
4. You'll see a confirmation that you're successfully signed in.