The non apache warning can be removed and is not related to your problem, I think.
Do you know the username for your GetSimple site? If so, you can click on "Forgot your password?" and you'll received a new one.
I suppose that your DirectAdmin username and password is not related to GS, but I don't know how that Installatron script works. If you cannot solve this, perhaps you should contact your host.
2019-03-26, 10:22:47 (This post was last modified: 2019-03-26, 10:26:51 by Tyblitz.)
Here's the installatron service: https://installatron.com/getsimple/install (I think it's commonly integrated into cPanel providers).
Btw, I once successfully installed GS on an Nginx server, but it did take some tweaking (essentially rewriting htaccess rules in Nginx-compatible format)