1. Download and install Android Studio (free) This is a huge download and the installation process can take a few hours to complete. Once installed, you'll want to update all the software that pops up. Restart your Android studio and when you get the all go, contuine to step #2
Android Studio Download Page https://developer.android.com/studio/index.html
2. Download the pacakge from your client download section. Only active SHOUTcast Widgets v5 clients will be able to download. https://shoutaccount.com/index.php?rp=/download/category/15/SHOUTcast-Widgets-v5.html
Publishing
You'll need a Developers Account to publish your app. Cost is a one time fee of $25 and is good for unlimited apps. https://play.google.com/apps/publish/