Installation gives blank page, no errors

See troubleshooting of drupal WSOD (white screen of death) - There is a hint that suggests add a piece of program code at the end of the index.php.

*********************************************************
<?php

error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);

// $Id: index.php,v 1.94 2007/12/26...
*********************************************************

Additional hints - s. https://drupal.org/node/158043

Why did you use the beta 3 instead of beta 4?

That is no problem of the version of oa2. Perhaps you have to upload all files again (upload process has broken or forgotten some files) or the environment of the server (php, php.ini, sql, my.cnf, settings.php or .htaccess) has to be modified.

E.g.:
In my case I have to comment out (with a '#') the Option-Statements in the .htaccess to access the installation.

But check what will be displayed if you add the mentioned lines in the index.php first.

Most likely issues with your hosted server config. Make sure your PHP memory_limit is 256M or higher.

Server Requirement
Apache Version : 2.2.22 or Higher
PHP Version: 5.3.27 or Higher
MySQL Version : 5.5.24 or Higher

PHP information:
max_execution_time: 120
max_input_time: 60
upload_max_filesize: 24M
post_max_size: 8M
memory_limit: 256M

Mysql information:
max_allowed_packet : 20M