1. PHP REQUIREMENT LINK: http://www.minibb.com/require.html
2. Configure $main_url as 'softurl' in setup_options.php while manual installation. Dont use the hardcoded default one i.e $main_url=(isset($_SERVER['HTTPS'])?'https':'http').'://'.$_SERVER['SERVER_ADDR'].pathinfo($_SERVER['SCRIPT_NAME'])['dirname']; as this would install the script in format of  URL : http://IP-ADDRESS/{{MINIBB}} and not domain name. This is also mentioned in their docs that, this should be set to a static value, {{PATH}}/templates/manual_eng.html(under $main_url).