Issue: In Microsoft Teams (Teams), in the default "Files" channel, it is only possible to add a Document Library as cloud storage. It is not possible to add a single file or folder. The Team will have access to all the files and folders in the Library.
Add file or sub folder to new tab as a website
1. Click on "+"
2. Click on the "Website" icon. The location might differ on your screen.
3. Paste the URL of the file/folder. Change the name of the Tab.
4. The newly created Tab should display the file/folder when clicked.
* It is recommended that you open Office files with the Desktop App.