How to create Digital Signage with Screenly on Raspberry Pi?

Does screenly have api support?

Load of steps missing, and steps are different for different versions of the Pi and stupid music.

strange instructional video.

Followed the instructions step by step but it's not booting

Step by step video, can't be easier.

Do we need to format the sd card first, or remove raspbian or anything? Or do we just flash Screenly onto the card that ships with the RPi without altering it?