Some Android players may have troubles syncing with Google Play. If you're receiving an Account Sync error message, ensure that your device is signed into the same Google Play ID that was originally synced with Commander.
To access your Google Play account, tap on your system's Settings and then on Account. Here you can log out and then log in with the account you originally used for Commander.
After having done this, reload Star Wars™: Commander.
If the previous steps don't solve the issue, it's recommended that you sync with Facebook instead of Google Play. Check the following article for steps on syncing your game to Facebook: