See the "Installing the required software" section from https://www.redhat.com/sysadmin/create-rpm-package to understand the directory structure.

Clone the repository

git clone https://github.com/FrostyX/rpmbuild-topdir.git ~/rpmbuild/

or

git clone [email protected]:FrostyX/rpmbuild-topdir.git ~/rpmbuild/