Clone the repo and initialize submodules:

git clone --recurse-submodules https://github.com/boutproject/BOUT-configs.git

Source setup-env.sh to activate the spack enviroment and install software dependencies (installation happens only the first time):

source setup-env.sh

There is a minimal cmake configuration script under scripts, invoke it at the same path where the BOUT-dev directory is and it will output a minimal, GPU-enabled configuration under a created build directory:

<path>/cmake-minimal.sh
cd build
make -j