Download the zip:
extract it, and copy commons-1.5.11.jar inside Cryptomator\app folder, and voilà, easy dark mode without paying for something is very bad coded.
virus scans if you’re scared:
Note: Despite I am releasing this, I don’t recommend use it for a professional working environment, since it doesn’t support symbolic links including the bunch of bugs built in.
Use VeraCrypt or something else instead…
Enjoy!