restore duplicator without installer.php file

Hi, I only have the .zip file of an old backup (2 years ago) made with duplicator lite.
I renamed the …..installer-backup.php file found in the installer.php zip file and tried to reinstall both locally and hosted but still the same error:
"[PHP ERR][FATAL] MSG:Uncaught TypeError: decoct(): Argument #1 ($num) must be of type int, string given in /opt/lampp/htdocs/dup/installer.php:607
Stack traces:

0 /opt/lampp/htdocs/dup/installer.php(607): decoct('u+rwx')

1 /opt/lampp/htdocs/dup/installer.php(583): DUPX_Bootstrap->setPermsOnItem('/opt/lampp/htdo…', 'u+rwx')

2 /opt/lampp/htdocs/dup/installer.php(566): DUPX_Bootstrap->setPerms('/opt/lampp/htdo…', 'u+rwx', false)

3 /opt/lampp/htdocs/dup/installer.php(497): DUPX_Bootstrap->fixInstallerPerms('http://localhos…')

4 /opt/lampp/htdocs/dup/installer.php(1608): DUPX_Bootstrap->run()

5 {main}

thrown [CODE:1|FILE:/opt/lampp/htdocs/dup/installer.php|LINE:607]
"

then I followed the following instructions:
"open installer.php
go to private function setPermsOnItem($path, $perms)
replace the entire content inside {}

if (($result = self :: chmod ($path, $perms)) === false) {
self :: log("ERROR: Couldn't set permissions of $path
");
} else {
self::log("Set permissions of $path
");
}
return $result;

/////////////// looks like this ////////////////

private function setPermsOnItem($path, $perms)
{
if (($result = self::chmod($path, $perms)) === false) {
self::log("ERROR: Couldn't set permissions of $path
");
} else {
self::log("Set permissions of $path
");
}
return $result;
}

//// i got it from duplicator\installer\installer.tpl ////"

But so it gives me error 500 both locally and on hosting.
What to do?