The job requires you to go through existing code (Appium+Java), improve it, add the changes requested and further work with us to solve the issues that we may face due to changes in targeted app.
The Appium code has to be run on real Android devices and no emulator is possible to use. If you own multiple Android devices you have higher chance of getting hired.
You may also need to run the code for some time to capture current code working as well as testing the new code/changes that you will be incorporating. When you bid for this project make sure your first line in the proposal is "AU" so that I know you have read the requirements.
The exact requirement about changes that needs to be done will be shared once you're hire for work.