these were helpful for me in setting it up...
For debian buster the PHP version is 7.3 so you have to edit a different file. The first grep will find your path to the files needed then you can modify that path at the end of the sed commands below.
Also need to remove index.html and chown the directory
Code:
grep -r short_open_tag /etc/php/
grep short_open_tag /etc/php/7.3/apache2/php.ini
grep short_open_tag /etc/php/7.3/cli/php.ini
sudo sed -i 's/short_open_tag\ =\ Off/short_open_tag\ =\ on/g' /etc/php/7.3/apache2/php.ini
sudo sed -i 's/short_open_tag\ =\ Off/short_open_tag\ =\ on/g' /etc/php/7.3/cli/php.ini
grep short_open_tag /etc/php/7.3/apache2/php.ini
grep short_open_tag /etc/php/7.3/cli/php.ini
sudo vi config.php
sudo rm index.html
sudo chown -R www-data:www-data /var/www/html/
systemctl restart apache2