The problem in running WRF-CROCO COUPLING

Hello, I encountered the following error when running the WRF-CROCO coupling model. I don’t know exactly where the problem is, would like to ask you how to solve it?

mpirun was unable to find the specified executable file, and therefore
did not launch the job. This error was first reported for process
rank 0; it may have occurred for other processes as well.

NOTE: A common cause for this error is misspelling a mpirun command
line parameter option (remember that mpirun interprets the first
unrecognized command line token as the executable).

Node: n38
Executable: app.conf

40 total processes failed to start