I was trying a new install on a new server. If we use the IP of the sever we can get the install page and the check list. If we use the domain which is a sub-domain we get Fatal error: Call to undefined function __() in /volume1/web/xibo18alpha/web/install/index.php on line 63
That is a in the notFound handler and was fixed here, although that is not the root cause of your issue.
The root cause is that the application cannot find the route requested - which may well be something to do with the rewrite rules (perhaps they are only being enabled when accessing via IP)
It was indeed the .htaccess rewrite was not correct. I think it has been fixed correctly, however now I get this address on clicking next from step 1 http://xibo.walidigital.com/install/2? with a 404 error.
Yes, some really strange things seem to happen when trying to use a Synology box with DSM 6. Certs are a bit funny too. Will see if ZMQ can be installed or not.