I can not understand why he writes
Can not find "java". Check if the name is correct and try again.
In the "system environment variables", I tried to add the path to java but to no avail
$cmd = 'java -jar C:/start.jar'; if (substr(php_uname(), 0, 7) == "Windows"){ pclose(popen("start /B ".$cmd, "r")); } else { exec($cmd." > /dev/null &", $PID); }