For this task you can clone the master branch of camb in a directory CAMB/ on the same level as this one. At some point it should become possible to use the public repository:
cd ..
git clone --recursive https://github.com/cmbant/CAMB
However, so far, a small bug makes input_4_cast incompatible with this version, and we use instead
cd ..
git clone --recursive https://github.com/santiagocasas/CAMB
then:
cd CAMB
python3 setup.py install [--user]
cd fortran
make camb
cd ../../Euclid_KP_nu