Post-installation configuration

I have just installed librenms on my Centos 7 server following instructions from the web.
All goes well until the final step where I browse to http://www.sdc.com.au/librenms expecting to see the configuration check page.
Instead, I get referred to http://sdc.com.au/librenms/install with a “File not found” error.
There is no install file anywhere in my /opt/librenms tree.
What have I missed?