Tap the App Store icon or the Google Play icon depending on the type of mobile device you have.The primary difference between the two installations is whether you press the App Store icon (iPhone) or the Play Store icon (Android). The first 3 steps are downloading the app. What to do once you have the app, begins at step 4 and is the same for either iPhone or Android.
The device shown is an iPhone, but installation on an Android device would be nearly the same. This document contains detailed instructions for installing Microsoft Teams on a mobile device and configuring it for use at Texarkana College.