1. In the desktop or web app, click Files Files button on the left side of the app, and then click Add cloud storage. Pick your cloud storage service from the list that comes up.
2. As of right now, you can share files from Box, Dropbox, Dropbox for Business, Google Drive, Egnyte, and Share File in Teams.
3. Sign in with your account. You might need to turn off your pop-up blocker first.
4. Now you can add files from the cloud as well as from your computer to channels.