We recommend to use the described way in https://makandracards.com/makandra/57341-rubymine-how-to-add-a-german-spell-checker instead of this card.
http://www.winedt.org/dict/de_neu.zip
unzip de_neu.zip
mkdir ~/Documents/dic
iconv -f UTF-16 -t UTF-8 de_neu.dic -o ~/Documents/dic/de_neu_utf8.dic
~/Documents/dic