RetDec IDA Pro plugin is not able to work with local RetDec installation as it is not able to first find sh command and after that, the paths provided by the pluigin are Windows system path (Z:*) which can't be understood by the decompiler. These two files fix that.
The first file sh.bat should be located in the PATH (I installed it at C:\windows). The second one (decompiler.sh) should be in /usr/bin on the host system.