Sorry you're having trouble with the app. I'm not sure how much experience you have with downloading apps from outside the store on android, so you might have to set some permissions to allow unauthorized apps to be installed. This link should get you started on that: https://www.lifewire.com/install-apk-on-android-4177185
If you're already familiar with installing these kinds of apks, let us know and we can try to troubleshoot.