We suspect there was an upload issue, so to head this off from future misunderstandings we publish here the fix we've sent to a couple of other people who have not downloaded apps before. You can use this fix for other apps you may have problems after or during downloading too.
Sometimes it can be the platform compatibility, a bad connection, more fingers than thumbs, storage space, payment problems or a lack of experience perhaps with a new phone. But just to say we have yet to have problems with the actual app once people have it working on their phone.
Here's a fix for if it ever says Invalid License:
If you receive an error message stating “Invalid License”, please make sure that you have a working internet connection by opening a web page on your internet browser, and try different sources (3G or Wi-Fi) if needed. You also want to make sure you are signed into the same Google Play account you used to originally purchase the app.
If this does not work, please follow these instructions to resolve the issue:
1. Go into “Settings > Apps” on your device
2. Tap on the “Google Play Store” application item and tap on it (Don't see it? Make sure 'All Apps' is selected)
3. Tap on "Force Stop", then tap on "Storage"
4. Tap on "Clear Cache" and "Clear Data" if active
5. Turn off your mobile device, unplug the battery (if applicable) for a couple of seconds and then plug it back in
6. Restart the device.