Out of curiosity, according to Docker Documentation:
When you install docker from repository, you should have dockerd-rootless-setuptool.sh in /usr/bin.
I installed Docker via sudo pacman -S --noconfirm docker docker-compose and the file was missing. If it is included in other distro repository, why not include it in the docker package as well? That way you do not need to rely on the AUR installation.
Also, for AUR you do not need pamac build because pamac install (without sudo) works just fine for this package… at least today. It will build automatically.