I see what you mean. But that means
http://IP/~admin/ is being processed with php-fpm chrooted from admin user? Might have some misconfiguration in my config then. Because my php code is only trying to access from /home/admin/template.local/owncloud/index.php other scripts and files inside /home/admin/template.local/owncloud/* not outside this dir.
When I have time, I'll generate a phpinfo() from there to check if we have "/home/admin/" in open_basedir, but I'm predicting I won't be able even to process the php file with <?php phpinfo(); ?> file itself, only html's, because I only have access to open_basedir directories that are in default.conf and nothing else. Since this domain doesn't resolve any IP (it's not mine), It's hard to access it other then
http://IP/~admin/ to debug it.
I have no resources to test it further. But I can provide you the VM if you want (it's just a playground VM).