ZecWallet Android is an Android frontend for the desktop ZecWallet that lets you send and receive shielded payments from your mobile phone. It's available on the Google Play Store. You can also head over to the Releases page to download an APK.
In order to let your Android phone connect to your desktop, you need to run the deskop ZecWallet, and sync a full zcash node.
After your node is synced, go to Apps -> Connect Mobile App to view the connection QR Code, which you can scan from the Android App.
If you're installing the APK directly, you'll need to allow Install from untrusted sources on your Android phone.
Detailed documentation is available on the docs site.
You can file issues in the issues tab.