Having trouble to get it to boot

I’m using a raspberry pi model b 3+.
I’ve downloaded NextCloudPi_RPi_10-04-18.img and flashed it with Etcher. When I load the SD Card into the pi - it doesn’t boot.

Do I need something else?

I’ve installed Raspian with NOOBS on the same SD card, that booted up fine. So, clearly, I’m missing something. :slight_smile:
Any help would be much appreciated.