Hi @patrickk83, and welcome.
I’ve never used Orekit on Android, but from your stacktrace it seems like the orekit-data files (basically model data required for nearly all Orekit methods) are not initialized properly. There is a topic here with links to the documentation.
There may be Android specificities since you will probably have to work with the file system or application packaging system. Looking at the Stavor source code linked by @bcazabonne might provide answers.