Why can't I install the software on my server?
 

I'm installing vBulletin 5 on my server these days. Or atleast I'm really trying to.
So I download the .zip. I upload it to the server. I unzip it, take away the folder not to be uploaded and enter the data into both config-files. The next step would be to enter the url to the install.php file and then watch vBulletin enter my site like magic, right?

What actually happens is that I get errorcode 500 from the browser and a message haunting me with complaints about my configurationing skills.

What am I doing wrong here?

(As you may magically allready have figured out, I'm not an expert in this area.)