Hi Ahmed_Shafei,
Rene here, an Outlook.com user like you and an Independent Advisor. Thank you for submitting your question. Let me try to assist you.
Please go to your Teams user profile > Settings then click on the General tab. Add a check-mark next to Register Teams as the chat app for Office (requires restarting Office applications).
If necessary, restart Teams and Outlook to apply the changes.
Let me know if this helps!