Posted by Precise Simulation on
URL: http://forum.featool.com/Simple-Test-Case-OpenFOAM-Error-tp1164p1425.html

Follow the link in the documentation https://www.featool.com/doc/openfoam#install_of_mpi, also it is not enough to download and copy, you must install the MPI binaries to your system so they are accessible to the toolbox (how to install programs and software depends on what type of system/OS you are using).