You have an issue because the script cannot find the location or path of the mpirun command.
Try the following command
which mpirun
If you get the message “no mpirun in (…)”
then you need to set up your mpi environment
If you are running on a server that has Environment Modules use the following command to find out what modules are available:
Modules let you load predefined environments, and in this case they’re used to load different MPI and compiler environments.
module avail
If there is a module for openmpi and gcc such as the following module: openmpi_4.0.1/gcc_9.1.0 you can load that module using the following:
module load openmpi_4.0.1/gcc_9.1.0
If you do not have access to a server that allows you to load modules to configure your environment, then you will need to install openmpi or intel mpi and then once that is installed add the path to your mpirun command to your PATH.
You can try to follow these instructions: