@sdetweil
Get an error message now:

pi@magicmirror:~ $ bash -c "$(curl -sL  https://www.dropbox.com/s/ah7wtk30101xx4t/test_screensaver.sh?dl=0)"
grep: ungültiges Argument „pms“ für „--directories“
Gültige Argumente sind:
  - „read“
  - „recurse“
  - „skip“
Usage: grep [OPTION]... PATTERNS [FILE]...
„grep --help“ liefert weitere Informationen.

Edit: And it still adds the configs to the autostart file, even if they already exist

@sdetweil
I tried again. The script ran without any console output.
As result the config:

@xset s noblank 
@xset s off 
@xset -dpms

was now doubled (first I added by hand, second from your script) in the file /etc/xdg/lxsession/LXDE-pi/autostart

Hello,
I had a similar problem. Just tried out some module configurations and forks.
I now use MMM-GoogleMapsTraffic from here https://github.com/sdetweil/MMM-GoogleMapsTraffic.git (see this thread MMM-GoogleMapsTraffic freezes Magic Mirror)
and MMM-MyCommute from here https://github.com/qistoph/MMM-MyCommute.git
This seems to work for me.
There is also a small error in your configuration. The first destination has a comma after the last configuration endTime. This needs to be removed for a propor JSON file.
Regards Dirk

Hello,
I ran this script a a fresh install of “Raspbian Buster with desktop, July 2019” on a Raspberry Pi 3 B. I got this output:

pi@magicmirror:~ $ bash -c "$(curl -sL  https://www.dropbox.com/s/ah7wtk30101xx4t/test_screensaver.sh?dl=0)"
some other screensaver bash
please configure it manually

I guess the latest Raspian shall be support. Fell free to ask me for some additional information or traces from my setup.
Regards Dirk

Edit:
Currently trying out this manual method: https://www.raspberrypi.org/forums/viewtopic.php?t=249837&p=1525721