Installation Step Four :: Post-Installation Checks Verify that file permissions for all files, including config.php, are set to CHMOD 644 (user: read/write, group and other: read only).
Directories should be CHMOD 755 (user: read/write/execute, group and other: read and execute). Alternatively, CHMOD 711 (user: read/write/execute, group and other: execute only) can be used.
Lastly, if the /install/ directory still exists, delete it using FTP, shell or you web host's control panel.
Enjoy your new forum!