This link contains all information about building cstor-operators from source, contribution guide, reaching out to contributors, maintainers etc.
If you want to build the cstor-operators right away then the following is the step:
mkdir -p $GOPATH/src/k8s.io
cd $GOPATH/src/k8s.io
git clone https://github.com/openebs/cstor-operators
cd cstor-operators
make all.amd64