@juanito aparnetemente este era el problema:
pero ahora me da este error al cargar la pagina
HTTP ERROR 500
y esto sale en el log:
[Wed Apr 15 01:27:54.208838 2020] [php7:error] [pid 20175] [client ::1:34766] PHP Fatal error: Uncaught Error: Call to undefined function mysqli_connect_error() in /var/www/html/ojs/lib/pkp/lib/adodb/drivers/adodb-mysqli.inc.php:777\nStack trace:\n#0 /var/www/html/ojs/lib/pkp/classes/install/PKPInstall.inc.php(82): ADODB_mysqli->ErrorMsg()\n#1 /var/www/html/ojs/lib/pkp/classes/install/Installer.inc.php(178): PKPInstall->preInstall()\n#2 /var/www/html/ojs/lib/pkp/classes/install/form/InstallForm.inc.php(195): Installer->execute()\n#3 /var/www/html/ojs/lib/pkp/pages/install/InstallHandler.inc.php(67): InstallForm->execute()\n#4 /var/www/html/ojs/lib/pkp/classes/core/PKPRouter.inc.php(390): InstallHandler->install(Array, Object(Request))\n#5 /var/www/html/ojs/lib/pkp/classes/core/PKPPageRouter.inc.php(231): PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(Request), Array, false)\n#6 /var/www/html/ojs/lib/pkp/classes/core/Dispatcher.inc.php(134): PKPPageRouter->route(Object(Request))\n#7 /var/www/html/ojs/lib/pkp/classes/core/PKPApplication.inc.php(252): Dispatcher->dispatch(Object(Request))\n#8 /var/www/ in /var/www/html/ojs/lib/pkp/lib/adodb/drivers/adodb-mysqli.inc.php on line 777, referer: http://localhost/ojs/index.php/index/install