It was not the question of free space! The app must be installed on the internal memory. These unsubscribe / remove the external SD card, then install that. After successful installation, the external SD card can be used again! Too bad that this information was not provided by the software developer, or it is unknown / was. In fact, multiple downloading was the final answer "Not Installed" extremely frustrating. But it was not in my case, at least at the HW !. Good luck to other Galaxy users, perhaps this is also the other models the solution?
