Additional chat-related features and issues within Microsoft Teams for Education
Hello Someone,
Based on the prompting message you mentioned above, it is more likely that the chat feature was disabled by your Teams Admin in the Teams Admin Center > Messaging policies > Chat. If it was disabled, your Teams Admin could enable it and assign the respective policy to your teams account. Please note the change would take 2-24 hours to take effect there, please wait for it with some more patience, thanks.
Moreover, for the admin, as your thread was posted on the Teams for Education category, if you are a student in the school, please contact your school IT department for further assistance, generally, the school IT will know who is the admin, thanks.
If you need any further helps, please feel free to share with me, thanks.
Best Regards,
Oliver