According to the User’s Guide Linux systems are recommended. However, I have a Mac and want to install it on that. Is there an option for that?
In principle it should work, probably with a bit of effort on your part. At least some of sathis has been done in the past with GNU the GNU gcc and Intel ifort compilers. You’ll need them, of course.
First, you’ll need the libraries for netCDF-C (libnetcdf.a) built with gcc and netCDF-Fortran (libnetcdff.a) built with ifort.
For the I/O API, there is a rather-old configuration file (2017, eight years ago) Makeinclude.Darwin_x86_64ifort for the GNU gcc and Intel ifort compilers. You should be able to build the I/O API library and then the M3Tools programs, much as in the build-instructions https://cjcoats.github.io/ioapi/AVAIL.html, using BIN=Darwin_x86_64ifort
Then SMOKE should be straightforward; you might have a look at The Easy Guide® for Building SMOKE.
Making the CMAQ build-system work on MacOS may be tricky; however, as a start you should be able to create a build-directory on a Linux system, copy it, and then modify the flags in the Makefile to match those from the I/O API’s Makeinclude.Darwin_x86_64ifort
Running CMAQ and SMOKE, I don’t know. Note that the standard run-scripts use the tcsh shell – is that available on MacOS? (if not, you’ll have to translate into whatever shell-script language you have.