Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi! Let me help you.
Please check if you can access Outlook Web.
And please check if your internet connection is stable.
Check that the date and time settings on your machine are correct; if not, please adjust them in Settings.
Try repairing Microsoft Office;
Press Windows + R, type control, and press Enter.
Go to Programs → Programs and Features.
Find Microsoft 365 or Microsoft Office in the list.
Select it, then click Change (or right-click it and select Change).
Choose Online Repair.
Click Repair, then confirm.
Wait for the repair to complete (this requires an internet connection).
Restart your PC, then test your Office apps again.