The whole process is described by creator Meliox in PVE Mods: node-sensor-readings-view. Here are the steps to perform in a root shell on your proxmox server:
# install lm-sensors and enable appropriate module(s)
apt install lm-sensors -y
sensors-detect # follow output guidance
echo "coretemp" >> /etc/modules # example for intel CPUs
# run install script
mkdir /opt/pve-mod-gui-sensors
cd /opt/pve-mod-gui-sensors
wget https://raw.githubusercontent.com/Meliox/PVE-mods/main/pve-mod-gui-sensors.sh
bash pve-mod-gui-sensors.sh install