pve-enterprise.list is blank, per the instructions.
Here is my sudo apt update return:
moxmanager@pve:~$ sudo apt update
Hit:1 http://security.debian.org/debian-security buster/updates InRelease
Hit:2 http://download.proxmox.com/debian/pve buster InRelease
Hit:3 http://ftp.debian.org/debian buster InRelease
Hit:4 http://ftp.debian.org/debian buster-updates InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
moxmanager@pve:~$