A channel’s file library looks similar to a chat’s file library but has a few extra features, including the ability to create Office documents right from Teams.
While viewing a channel’s file library, click the New button.
You can create a subfolder in a file library or create an Office document.
Select a file type.
Enter a file name and click Create.
An online version of the associated Office app opens up right in the Teams window. Any changes to the document are automatically saved.
Modify the document and click Close when finished.
The instance of the Office app closes, and you return to the file library.