Same for me. It worked about 2 weeks ago.
It says they are doing server maintenance, the 500 comes from the wrong url being redirected to, I removed everything after the first / in the url and it showed correctly.
When I removed everything after the first /, I see this notice:
Evolution CMS - Server Maintenance
We are currently carrying out maintenance on the server and website and hope to be back shortly
Your Evo Team
I must wait until the website is back. I hope soon.
Heads up:
The server is currently being changed due to a transfer, but it seems to be taking longer than expected - I will look at this again in the morning.
Re-writes are no-longer in place on the current (old) server, that's why the 500 appears.
The docs will be back online as soon as the transfer has gone through - sorry for causing any problems, but this has to take place as I am no-longer in a position to maintain the documentation in the manner they should be.
My day job and completing a "BA Hons" are both taking all my time, so I have opted to give the site into good hands - the official Evo DEV team.