Install the QMCkl library (see upstream instructions)
./manual_install_pyqmckl.sh which should do the following
Copy the produced _pyqmckl.so and pyqmckl.py files into your working directory and do not forget to import pyqmckl in your Python scripts

The second step executes the following under the hood:

./build_pyqmckl.sh
<c-compiler> -I/usr/include/python3.8 -c -fPIC pyqmckl_wrap.c to compile the wrapper code into an object file using the <c-compiler> (replace with your C compiler, e.g. gcc) on your machine
<c-compiler> -shared pyqmckl_wrap.o -lqmckl -o _pyqmckl.so to produce the final C extension (this requires the qmckl library to be installed and present in the linking paths together with all its dependencies like trexio)

Python-ic installation (recommended)

Install the QMCkl library (see upstream instructions)
./pip_install_pyqmckl.sh

The last step runs ./build_pyqmckl.sh, copies the result into the pyqmckl/ directory and then runs pip install . to install the pyqmckl Python package in your environment.

SWIG pre-processing

Both aforementioned steps call build_pyqmckl.sh script which does the following pre-processing for SWIG

Copy the latest qmckl.h file fron include/ into the src/ directory
python process_header.py to generate pyqmckl_include.i list of SWIG patterns
swig -python -py3 -builtin -threads -o pyqmckl_wrap.c pyqmckl.i to generate the SWIG wrapper code in C and pyqmckl.py module in Python. Note: for this to work three files have to be present in the working directory: pyqmckl.i, pyqmckl_include.i and numpy.i.