Maestral has been shown to run on Raspberry Pi but requires at least Python 3.6 while, as of this writing, Raspbian comes preinstalled with versions 2.7 and 3.5. You will therefore need to build Python 3.6 yourself. Build instructions can be found for example here.
If you would like to use the GUI, you will also need to build PyQt5 since (for the time
being) there is no pre-built wheel for arm64. Due to the low amount of memory on a Pi 3,
the build will fail unless you temporary disable the Desktop GUI. To do that, run
Desktop/CLI and then choose the second option.
After rebooting the system, you should have enough memory to build
PyQt5. So just run
$ python3.6 -m pip install --upgrade maestral[gui]
PyQt5 may take a couple of hours. If the build keeps failing for low
memory, you might need to temporary stop some services running in the background (like
webserver, squid, etc). After everything is finished successfully, run the
config again, reboot and enjoy your Maestral installation!
Currently, the “Start on login” option of the GUI does not support the Raspbian Desktop.
If you want the GUI to run on startup, first make an executable sh file containing
maestral gui. Then edit
/home/pi/.config/lxsession/LXDE-pi/autostart and add to a
new line @ followed by the sh file path.