I hope you sourced all the modeller binaries after the installation of
modeller. If not kindly source all the binaries (which locates under the
bin directory) via placing them in .bashrc file.
you should have the below details in your ~/.bashrc file.
This is only necessary if you installed Modeller using the .tar.gz
installer. Aparna is on a Mac, which has already installed Modeller in
the default paths - no modifications to .bashrc are needed.