Hi Ronald,
Sarah is correct, the app will only run on Android 4.4 (KitKat) or higher. I will say that devices running KitKat will likely be running pretty slowly though!
If you have an older version of Android, you can install the older version of my app that worked down to Android 3 (I think).
You'll find it on the downloads page (
https://www.opensongapp.com/downloads) - The version you need is v3.9.6. Please note that if you use this, there may be lots of broken stuff (e.g. UG downloads, etc.) and you won't have any of the features added since the v4 update. However, if you were using this before, you'll know that.
You could try manually installing a newer version from the downloads page, but you'll likely find the app may crash when it comes across code that older versions of Android can't cope with (this may also happen when you try to install it).