The latest version of Sub Rosa Pro on Android only supports Android 6.0 and higher. 

If you are running Android OS version 5 or earlier, you will not be able to install the current release of Sub Rosa Pro.

The last version of Sub Rosa Pro that supports Android 5 is version 4.0.0.

If you are running Android version 5 with Sub Rosa Pro version 4.0.3, and are unable to use the app, then you should update to a newer OS. If you are unable to update your OS please contact support for assistance.