I have just tried to install the latest RC in the latest Joomla 3.6RC and have the issue that I can't install.
Php 7.0.7 (I am aware there is an updated version but not able to install it at the moment, the installer hangs having created the admin menu's looking in the logs I can see the below.
AH01071:
Got error 'PHP message: PHP Notice: Use of undefined constant KPATH_ADMIN - assumed 'KPATH_ADMIN' in /var/www/vhosts/website/website/administrator/components/com_kunena/install/schema.php on line 13\nPHP message: PHP Notice: Use of undefined constant KPATH_ADMIN - assumed 'KPATH_ADMIN' in /var/www/vhosts/website/website/administrator/components/com_kunena/install/schema.php on line 14\nPHP message: PHP Warning: DOMDocument::load(): I/O warning : failed to load external entity "/var/www/vhosts/website/website/administrator/KPATH_ADMIN/install/install.xml" in /var/www/vhosts/website/website/administrator/components/com_kunena/install/schema.php on line 363\nPHP message: PHP Notice: Trying to get property of non-object in /var/www/vhosts/website/website/administrator/components/com_kunena/install/schema.php on line 499\nPHP message: PHP Warning: Invalid argument supplied for foreach() in /var/www/vhosts/website/website/administrator/components/com_kunena/install/schema.php on line 529\n', referer: http://website/administrator/index.php?option=com_kunena
When I use PHP 5.6.22 I have no issues installing. Hopefully I can close this down when I am able to update my PHP version on the server.