On Bullseye you need to install WiringPi first:

git clone https://github.com/WiringPi/WiringPi.git

cd ~/wiringPi
$ ./build

raspberry-s0-bus-stromzaehler-logger

PIN 5 / GPIO 3 = +
PIN 34 = GROUND

change BUTTON_PIN var in strom.c

See WiringPi Pinout
GPIO 3 = 9 in WiringPi

Compile

gcc -lwiringPi -o strom strom.c

Edit service
sudo cp service /etc/init.d/stromlogger
sudo cp service_watt /etc/init.d/wattlogger

sudo chmod 755 /etc/init.d/stromlogger
sudo chmod 755 /etc/init.d/wattlogger

cd /etc/init.d/

sudo update-rc.d stromlogger defaults sudo update-rc.d wattlogger defaults

control service

sudo service stromlogger stop
sudo service stromlogger start
sudo service stromlogger restart

sudo service wattlogger stop
sudo service wattlogger start
sudo service wattlogger restart