1. Go to AppExchange to install the app
2. Login to Production or Developer Edition org where you would like to install the app
3. Click “Get It Now” button
4. Select “Install in Production” or “Install in Sandbox”
5. Select “terms and condition” checkbox and click “Confirm and Install
6. Select “Install for All Users” and click “Install”. This is recommended approach because it will apply all necessary permissions to the profiles for this app. You can easily provision/revoke access to certain users using manage license option.
You should get an email notification once the app is successfully installed. Usually it takes about 2-3 minutes for installation.