“Warning: Server Setup non-Apache” (GS 3.3.13)

[GetSimpOwl]

On the login page (/admin) of my site, a red-box says, “Warning: Server Setup non-Apache”.

I installed GS 3.3.13 on a hosting server with DirectAdmin control panel, using the auto-installer Installatron.

I updated my username and password combination in the Control Panel, but still cannot log in.

How can I fix this?

Thanks.