Bought and pressed download but no response. Pressed 3 times in total I guess and after a while got error message saying not enough space in rootfs. But then the app manager started the installation, and the size info was 13kb, too. Wonder if it was a corrupted file but went ahead with the installation and the game ran fine.

In short, be patient!

IMO, Microb should show an notification, or at the very least OVI Store web page could display a message like "Downloading application..."