If you track want to track app download & install from Web / WAP Property, UTM is the best method to track the same. You can also customize source value based on different conditions.
If ABC company launched an App for there customers. They customers those who are coming to WEB & WAP Property can be migrated to App Users. Through UTM, we can customize the source to understand where the installs happened through direct, organic, cpc, web & Wap property.