The script will give options to Disable the Enterprise Repo, Add/Correct PBS Sources, Enable the No-Subscription Repo, Add Test Repo, Disable Subscription Nag, Update Proxmox Backup Server and Reboot PBS.
Run the command below in the Proxmox Backup Server Shell. 
Proxmox Backup Server ONLY
bash -c "$(wget -qLO - https://github.com/community-scripts/ProxmoxVE/raw/main/misc/post-pbs-install.sh)"
It is recommended to answer “yes” (y) to all options presented during the process.