It didn't work?Here is some things you may try:
Make sure to enable sideloading on your device. On some devices only enabling developer mode may be possible. It could be that we sometimes distribute debug builds where you have to enable developer mode.
You must install our certificate. This will make your device trust ZellaSoft signed packages, i.e. packages distributed through Zella Store.
Make sure to have the "App Installer" app on your device.