Microsoft Teams is a easy to use tool that everyone with a BCC account has access to. Teams allows for easy file sharing, communication by messages or video chat, and much more.
Check out our how-to on Getting Started with MS Teams.
This will show you how to log in and install the full version of Teams which unlockes all the features.
Here's a video on how to create a team and add members.
After your team is created, if you need to add more members, follow these instructions provided by Microsoft.