VERY Strange. It shows up in the store IF I'm not logged on. As soon as I'm logged on and make my 1520 my current phone, it disappears! So its a bug, not compatible with 1520 (screen resolution?) or with WP8.1 GDR1 (don't know if you are on that). The descriptuion says 8.1 compatible.
Have you tried a manual download (while not logged on) and install from SD card?