After banging my head against this for too many hours, I think I can describe the problem, and suggest a work around. The fatal error in the installation from the OP ("Unable to set current step. Unknown step: login") is due to the plugins that are failing to install with the "Permissions error"; and the permissions error is because the automatic login as Admin has not worked. In my original setup, I was running the server on my laptop as localhost:8080 and I noticed that the install was trying to set a cookie in domain 'localhost:8080' - I believe the port number was causing a problem, and the cookie would not be returned in the next request, so the installation decides you are not logged in and not permitted to install the plugins. This would also explain the errors we see about having to enable cookies, when cookies are working just fine... To fix this I have done 2 things: set a 3 level domain name in my hosts file that points to 127.0.0.1 (ie revive.localhost.com)stopped trying to use a port number, and just listen on port 80Now a fresh install correctly sets a sessionId cookie in the domain '.revive.localhost.com', the plugins install fine, and I can actually login to the test server again.