We're happy to let you know that Screenly Pro now supports the Raspberry Pi 3 Model B+. To use the Raspberry Pi 3 Model B+, you need to use the disk image "screenly-v2-pi3-2018-11-09" or later. If you get a rainbow screen when you boot up your device, you're using an older image.
You should always use the official Raspberry Pi power supply.
3.5 Audio jack is currently non-operable.