Have you also started the mungemunge service?
Make sure to start it as well by using systemctlsystemctl as follows.
sudo systemctl start munge sudo systemctl status munge.
sudo systemctl start munge
sudo systemctl status munge
I recommend you follow this guidethis guide I wrote on how to install Slurm in a single node environment for Ubuntu 22.04.
https://medium.com/@pausantanapi2/slurm-single-node-installation-on-ubuntu-22-04-6479e70f7911
Cheers.