This error refers to Proclaim is having difficulty to communicate with Outlook.
1) Make sure user Mail and Proclaim Profile is connected Check Related Article.
2) If Outlook is not opening then we would need to Repair the Office. Speak to IT or Follow the steps below:
On the Windows Start screen, type Control Panel.
Click or tap Control Panel.
Under Programs, click or tap Uninstall a program.
Click or tap Microsoft 365, and then click or tap Change.
Click or tap QuickRepair, and then click or tap Repair. You may have to restart your computer after the repair process is complete.
3) Try logging into Proclaim again.