First make sure to enable the Podman socket:
systemctl enable --now podman.socket
Run the Portainer agent in a Podman root environment:
podman run -d --privileged \
-p 9001:9001 \
--name portainer_agent \
--restart=always \
-v /run/podman/podman.sock:/var/run/docker.sock:Z \
-v /var/lib/containers/storage/volumes:/var/lib/docker/volumes \
portainer/agent:2.18.4
credits: here