Resolution:  To add third party applications to Teams, follow the steps below:

1. On the left side of Teams, click on the button that says 'Apps'

2. Using the built in search tool or categories, look for an application you want to add to Teams

3. Once you locate the application you want to add, hit the Add button the right side of the screen

4. In the window that appears, again press the Add button

5. Once done, you will be able to launch the application