These directions are for iOS/Apple devices but the general idea is the same for Android.
Step 1: Swipe in the middle of your home screen downwards to reveal the search
Step 2: Type in “app” and click on the App Store.
Step 3: Type in “teams” into the search and hit search.
Your icon may say “Get” (if it’s not installed aleady), “Download” (cloud icon with an arrow down), or “Open” (installed already). This program should be free. Do not download any that has a cost.